From 216e21a1fa95ffc87c371cdd6262467df8cdb5cd Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Tue, 16 Nov 2021 01:15:21 +0100
Subject: [PATCH] AK: Convert AK::Format formatting helpers to returning
 ErrorOr<void>

This isn't a complete conversion to ErrorOr<void>, but a good chunk.
The end goal here is to propagate buffer allocation failures to the
caller, and allow the use of TRY() with formatting functions.
---
 AK/DistinctNumeric.h                          |   2 +-
 AK/Error.h                                    |  11 -
 AK/FixedPoint.h                               |   4 +-
 AK/Format.cpp                                 | 226 ++++++++++--------
 AK/Format.h                                   | 115 +++++----
 AK/IPv4Address.h                              |   2 +-
 AK/JsonValue.h                                |   4 +-
 AK/LexicalPath.h                              |   4 +-
 AK/NonnullOwnPtr.h                            |   4 +-
 AK/NonnullRefPtr.h                            |   4 +-
 AK/RefPtr.h                                   |   4 +-
 AK/SourceLocation.h                           |   2 +-
 AK/String.cpp                                 |   2 +-
 AK/StringBuilder.h                            |   2 +-
 AK/StringImpl.h                               |   4 +-
 AK/UFixedBigInt.h                             |   9 +-
 AK/URL.h                                      |   4 +-
 AK/Utf16View.h                                |   4 +-
 AK/WeakPtr.h                                  |   4 +-
 Kernel/Arch/x86/IO.h                          |   2 +-
 Kernel/Bus/PCI/Definitions.h                  |   4 +-
 Kernel/FileSystem/InodeIdentifier.h           |   2 +-
 Kernel/KBufferBuilder.h                       |   2 +-
 Kernel/KString.h                              |  15 +-
 Kernel/Library/ThreadSafeNonnullRefPtr.h      |   4 +-
 Kernel/Library/ThreadSafeRefPtr.h             |   4 +-
 Kernel/Library/ThreadSafeWeakPtr.h            |   6 +-
 Kernel/Memory/VirtualRange.h                  |   2 +-
 Kernel/PhysicalAddress.h                      |   2 +-
 Kernel/Process.h                              |   2 +-
 Kernel/Thread.cpp                             |   2 +-
 Kernel/Thread.h                               |   2 +-
 Kernel/VirtualAddress.h                       |   2 +-
 Tests/AK/TestFormat.cpp                       |   8 +-
 Tests/LibM/test-math.cpp                      |  17 +-
 .../UserspaceEmulator/ValueWithShadow.h       |   2 +-
 Userland/Games/Hearts/Player.h                |   4 +-
 Userland/Libraries/LibCards/Card.h            |   4 +-
 Userland/Libraries/LibCards/CardStack.h       |   4 +-
 Userland/Libraries/LibCore/FileWatcher.h      |   8 +-
 Userland/Libraries/LibCore/Object.h           |   2 +-
 Userland/Libraries/LibCore/SocketAddress.h    |   2 +-
 Userland/Libraries/LibCrypto/ASN1/DER.cpp     |   2 +-
 Userland/Libraries/LibCrypto/ASN1/DER.h       |   2 +-
 .../LibCrypto/BigInt/UnsignedBigInteger.cpp   |   4 +-
 .../LibCrypto/BigInt/UnsignedBigInteger.h     |   2 +-
 .../Libraries/LibDSP/ProcessorParameter.h     |   8 +-
 Userland/Libraries/LibGUI/ModelIndex.h        |   5 +-
 .../Libraries/LibGUI/PersistentModelIndex.h   |   2 +-
 Userland/Libraries/LibGUI/TextPosition.h      |   8 +-
 Userland/Libraries/LibGUI/TextRange.h         |   5 +-
 Userland/Libraries/LibGfx/AffineTransform.h   |   2 +-
 Userland/Libraries/LibGfx/BMPLoader.cpp       |   4 +-
 Userland/Libraries/LibGfx/Color.cpp           |   4 +-
 Userland/Libraries/LibGfx/Color.h             |   2 +-
 Userland/Libraries/LibGfx/Point.h             |   4 +-
 Userland/Libraries/LibGfx/Rect.h              |   4 +-
 Userland/Libraries/LibGfx/Size.h              |   4 +-
 Userland/Libraries/LibGfx/Vector2.h           |   4 +-
 Userland/Libraries/LibGfx/Vector3.h           |   4 +-
 Userland/Libraries/LibGfx/Vector4.h           |   4 +-
 Userland/Libraries/LibJS/Bytecode/Label.h     |   2 +-
 Userland/Libraries/LibJS/Bytecode/Register.h  |   2 +-
 Userland/Libraries/LibJS/Heap/Cell.h          |   6 +-
 .../LibJS/Runtime/PropertyAttributes.h        |   4 +-
 .../LibJS/Runtime/PropertyDescriptor.h        |   4 +-
 .../Libraries/LibJS/Runtime/PropertyKey.h     |  11 +-
 Userland/Libraries/LibJS/Runtime/Value.h      |   4 +-
 Userland/Libraries/LibPDF/Command.h           |   4 +-
 Userland/Libraries/LibPDF/Document.h          |  20 +-
 Userland/Libraries/LibPDF/Object.h            |   8 +-
 Userland/Libraries/LibPDF/Parser.cpp          |  12 +-
 Userland/Libraries/LibPDF/Renderer.h          |  58 ++---
 Userland/Libraries/LibPDF/Value.h             |   4 +-
 Userland/Libraries/LibPDF/XRefTable.h         |   8 +-
 Userland/Libraries/LibRegex/RegexMatch.h      |   2 +-
 .../LibWasm/AbstractMachine/Validator.h       |  12 +-
 Userland/Libraries/LibWeb/CSS/MediaQuery.h    |  12 +-
 Userland/Libraries/LibWeb/CSS/Selector.h      |   4 +-
 Userland/Libraries/LibWeb/DOM/Position.h      |   4 +-
 Userland/Services/LookupServer/DNSAnswer.cpp  |  44 ++--
 Userland/Services/LookupServer/DNSAnswer.h    |   4 +-
 Userland/Services/LookupServer/DNSName.h      |   2 +-
 Userland/Shell/AST.cpp                        |  47 ++--
 Userland/Shell/AST.h                          |   2 +-
 Userland/Utilities/strace.cpp                 |  29 ++-
 Userland/Utilities/syscall.cpp                |   2 +-
 87 files changed, 450 insertions(+), 448 deletions(-)

diff --git a/AK/DistinctNumeric.h b/AK/DistinctNumeric.h
index 77bb7058d7f..c6d98b66bc9 100644
--- a/AK/DistinctNumeric.h
+++ b/AK/DistinctNumeric.h
@@ -271,7 +271,7 @@ private:
 
 template<typename T, typename X, bool Incr, bool Cmp, bool Bool, bool Flags, bool Shift, bool Arith>
 struct Formatter<DistinctNumeric<T, X, Incr, Cmp, Bool, Flags, Shift, Arith>> : Formatter<T> {
-    void format(FormatBuilder& builder, DistinctNumeric<T, X, Incr, Cmp, Bool, Flags, Shift, Arith> value)
+    ErrorOr<void> format(FormatBuilder& builder, DistinctNumeric<T, X, Incr, Cmp, Bool, Flags, Shift, Arith> value)
     {
         return Formatter<T>::format(builder, value.value());
     }
diff --git a/AK/Error.h b/AK/Error.h
index fcc08d3008d..1346cb02d97 100644
--- a/AK/Error.h
+++ b/AK/Error.h
@@ -6,7 +6,6 @@
 
 #pragma once
 
-#include <AK/Format.h>
 #include <AK/Optional.h>
 #include <AK/StringView.h>
 #include <AK/Try.h>
@@ -131,16 +130,6 @@ private:
     Optional<ErrorType> m_error;
 };
 
-template<>
-struct Formatter<Error> : Formatter<FormatString> {
-    void format(FormatBuilder& builder, Error const& error)
-    {
-        if (error.is_errno())
-            return Formatter<FormatString>::format(builder, "Error(errno={})", error.code());
-        return Formatter<FormatString>::format(builder, "Error({})", error.string_literal());
-    }
-};
-
 }
 
 using AK::Error;
diff --git a/AK/FixedPoint.h b/AK/FixedPoint.h
index 110f15a4de6..f50e514b351 100644
--- a/AK/FixedPoint.h
+++ b/AK/FixedPoint.h
@@ -322,10 +322,10 @@ struct Formatter<FixedPoint<precision, Underlying>> : StandardFormatter {
     {
     }
 
-    void format(FormatBuilder& builder, FixedPoint<precision, Underlying> value)
+    ErrorOr<void> format(FormatBuilder& builder, FixedPoint<precision, Underlying> value)
     {
         Formatter<double> formatter { *this };
-        formatter.format(builder, (double)value);
+        return formatter.format(builder, (double)value);
     }
 };
 
diff --git a/AK/Format.cpp b/AK/Format.cpp
index fb95978873d..f0aa893a644 100644
--- a/AK/Format.cpp
+++ b/AK/Format.cpp
@@ -75,15 +75,15 @@ static constexpr size_t convert_unsigned_to_string(u64 value, Array<u8, 128>& bu
     return used;
 }
 
-void vformat_impl(TypeErasedFormatParams& params, FormatBuilder& builder, FormatParser& parser)
+ErrorOr<void> vformat_impl(TypeErasedFormatParams& params, FormatBuilder& builder, FormatParser& parser)
 {
     const auto literal = parser.consume_literal();
-    builder.put_literal(literal);
+    TRY(builder.put_literal(literal));
 
     FormatParser::FormatSpecifier specifier;
     if (!parser.consume_specifier(specifier)) {
         VERIFY(parser.is_eof());
-        return;
+        return {};
     }
 
     if (specifier.index == use_next_index)
@@ -92,9 +92,9 @@ void vformat_impl(TypeErasedFormatParams& params, FormatBuilder& builder, Format
     auto& parameter = params.parameters().at(specifier.index);
 
     FormatParser argparser { specifier.flags };
-    parameter.formatter(params, builder, argparser, parameter.value);
-
-    vformat_impl(params, builder, parser);
+    TRY(parameter.formatter(params, builder, argparser, parameter.value));
+    TRY(vformat_impl(params, builder, parser));
+    return {};
 }
 
 } // namespace AK::{anonymous}
@@ -189,20 +189,23 @@ bool FormatParser::consume_replacement_field(size_t& index)
     return true;
 }
 
-void FormatBuilder::put_padding(char fill, size_t amount)
+ErrorOr<void> FormatBuilder::put_padding(char fill, size_t amount)
 {
     for (size_t i = 0; i < amount; ++i)
-        m_builder.append(fill);
+        TRY(m_builder.try_append(fill));
+    return {};
 }
-void FormatBuilder::put_literal(StringView value)
+ErrorOr<void> FormatBuilder::put_literal(StringView value)
 {
     for (size_t i = 0; i < value.length(); ++i) {
-        m_builder.append(value[i]);
+        TRY(m_builder.try_append(value[i]));
         if (value[i] == '{' || value[i] == '}')
             ++i;
     }
+    return {};
 }
-void FormatBuilder::put_string(
+
+ErrorOr<void> FormatBuilder::put_string(
     StringView value,
     Align align,
     size_t min_width,
@@ -216,21 +219,23 @@ void FormatBuilder::put_string(
         value = value.substring_view(0, used_by_string);
 
     if (align == Align::Left || align == Align::Default) {
-        m_builder.append(value);
-        put_padding(fill, used_by_padding);
+        TRY(m_builder.try_append(value));
+        TRY(put_padding(fill, used_by_padding));
     } else if (align == Align::Center) {
         const auto used_by_left_padding = used_by_padding / 2;
         const auto used_by_right_padding = ceil_div<size_t, size_t>(used_by_padding, 2);
 
-        put_padding(fill, used_by_left_padding);
-        m_builder.append(value);
-        put_padding(fill, used_by_right_padding);
+        TRY(put_padding(fill, used_by_left_padding));
+        TRY(m_builder.try_append(value));
+        TRY(put_padding(fill, used_by_right_padding));
     } else if (align == Align::Right) {
-        put_padding(fill, used_by_padding);
-        m_builder.append(value);
+        TRY(put_padding(fill, used_by_padding));
+        TRY(m_builder.try_append(value));
     }
+    return {};
 }
-void FormatBuilder::put_u64(
+
+ErrorOr<void> FormatBuilder::put_u64(
     u64 value,
     u8 base,
     bool prefix,
@@ -271,64 +276,69 @@ void FormatBuilder::put_u64(
     const auto used_by_field = used_by_prefix + used_by_digits;
     const auto used_by_padding = max(used_by_field, min_width) - used_by_field;
 
-    const auto put_prefix = [&]() {
+    const auto put_prefix = [&]() -> ErrorOr<void> {
         if (is_negative)
-            m_builder.append('-');
+            TRY(m_builder.try_append('-'));
         else if (sign_mode == SignMode::Always)
-            m_builder.append('+');
+            TRY(m_builder.try_append('+'));
         else if (sign_mode == SignMode::Reserved)
-            m_builder.append(' ');
+            TRY(m_builder.try_append(' '));
 
         if (prefix) {
             if (base == 2) {
                 if (upper_case)
-                    m_builder.append("0B");
+                    TRY(m_builder.try_append("0B"));
                 else
-                    m_builder.append("0b");
+                    TRY(m_builder.try_append("0b"));
             } else if (base == 8) {
-                m_builder.append("0");
+                TRY(m_builder.try_append("0"));
             } else if (base == 16) {
                 if (upper_case)
-                    m_builder.append("0X");
+                    TRY(m_builder.try_append("0X"));
                 else
-                    m_builder.append("0x");
+                    TRY(m_builder.try_append("0x"));
             }
         }
+        return {};
     };
-    const auto put_digits = [&]() {
+
+    const auto put_digits = [&]() -> ErrorOr<void> {
         for (size_t i = 0; i < used_by_digits; ++i)
-            m_builder.append(buffer[i]);
+            TRY(m_builder.try_append(buffer[i]));
+        return {};
     };
 
     if (align == Align::Left) {
         const auto used_by_right_padding = used_by_padding;
 
-        put_prefix();
-        put_digits();
-        put_padding(fill, used_by_right_padding);
+        TRY(put_prefix());
+        TRY(put_digits());
+        TRY(put_padding(fill, used_by_right_padding));
     } else if (align == Align::Center) {
         const auto used_by_left_padding = used_by_padding / 2;
         const auto used_by_right_padding = ceil_div<size_t, size_t>(used_by_padding, 2);
 
-        put_padding(fill, used_by_left_padding);
-        put_prefix();
-        put_digits();
-        put_padding(fill, used_by_right_padding);
+        TRY(put_padding(fill, used_by_left_padding));
+        TRY(put_prefix());
+        TRY(put_digits());
+        TRY(put_padding(fill, used_by_right_padding));
     } else if (align == Align::Right) {
         const auto used_by_left_padding = used_by_padding;
 
         if (zero_pad) {
-            put_prefix();
-            put_padding('0', used_by_left_padding);
-            put_digits();
+            TRY(put_prefix());
+            TRY(put_padding('0', used_by_left_padding));
+            TRY(put_digits());
         } else {
-            put_padding(fill, used_by_left_padding);
-            put_prefix();
-            put_digits();
+            TRY(put_padding(fill, used_by_left_padding));
+            TRY(put_prefix());
+            TRY(put_digits());
         }
     }
+    return {};
 }
-void FormatBuilder::put_i64(
+
+ErrorOr<void> FormatBuilder::put_i64(
     i64 value,
     u8 base,
     bool prefix,
@@ -342,11 +352,12 @@ void FormatBuilder::put_i64(
     const auto is_negative = value < 0;
     value = is_negative ? -value : value;
 
-    put_u64(static_cast<u64>(value), base, prefix, upper_case, zero_pad, align, min_width, fill, sign_mode, is_negative);
+    TRY(put_u64(static_cast<u64>(value), base, prefix, upper_case, zero_pad, align, min_width, fill, sign_mode, is_negative));
+    return {};
 }
 
 #ifndef KERNEL
-void FormatBuilder::put_f64(
+ErrorOr<void> FormatBuilder::put_f64(
     double value,
     u8 base,
     bool upper_case,
@@ -362,25 +373,25 @@ void FormatBuilder::put_f64(
 
     if (isnan(value) || isinf(value)) [[unlikely]] {
         if (value < 0.0)
-            string_builder.append('-');
+            TRY(string_builder.try_append('-'));
         else if (sign_mode == SignMode::Always)
-            string_builder.append('+');
+            TRY(string_builder.try_append('+'));
         else if (sign_mode == SignMode::Reserved)
-            string_builder.append(' ');
+            TRY(string_builder.try_append(' '));
 
         if (isnan(value))
-            string_builder.append(upper_case ? "NAN"sv : "nan"sv);
+            TRY(string_builder.try_append(upper_case ? "NAN"sv : "nan"sv));
         else
-            string_builder.append(upper_case ? "INF"sv : "inf"sv);
-        put_string(string_builder.string_view(), align, min_width, NumericLimits<size_t>::max(), fill);
-        return;
+            TRY(string_builder.try_append(upper_case ? "INF"sv : "inf"sv));
+        TRY(put_string(string_builder.string_view(), align, min_width, NumericLimits<size_t>::max(), fill));
+        return {};
     }
 
     bool is_negative = value < 0.0;
     if (is_negative)
         value = -value;
 
-    format_builder.put_u64(static_cast<u64>(value), base, false, upper_case, false, Align::Right, 0, ' ', sign_mode, is_negative);
+    TRY(format_builder.put_u64(static_cast<u64>(value), base, false, upper_case, false, Align::Right, 0, ' ', sign_mode, is_negative));
 
     if (precision > 0) {
         // FIXME: This is a terrible approximation but doing it properly would be a lot of work. If someone is up for that, a good
@@ -401,19 +412,20 @@ void FormatBuilder::put_f64(
         }
 
         if (zero_pad || visible_precision > 0)
-            string_builder.append('.');
+            TRY(string_builder.try_append('.'));
 
         if (visible_precision > 0)
-            format_builder.put_u64(static_cast<u64>(value), base, false, upper_case, true, Align::Right, visible_precision);
+            TRY(format_builder.put_u64(static_cast<u64>(value), base, false, upper_case, true, Align::Right, visible_precision));
 
         if (zero_pad && (precision - visible_precision) > 0)
-            format_builder.put_u64(0, base, false, false, true, Align::Right, precision - visible_precision);
+            TRY(format_builder.put_u64(0, base, false, false, true, Align::Right, precision - visible_precision));
     }
 
-    put_string(string_builder.string_view(), align, min_width, NumericLimits<size_t>::max(), fill);
+    TRY(put_string(string_builder.string_view(), align, min_width, NumericLimits<size_t>::max(), fill));
+    return {};
 }
 
-void FormatBuilder::put_f80(
+ErrorOr<void> FormatBuilder::put_f80(
     long double value,
     u8 base,
     bool upper_case,
@@ -428,25 +440,25 @@ void FormatBuilder::put_f80(
 
     if (isnan(value) || isinf(value)) [[unlikely]] {
         if (value < 0.0l)
-            string_builder.append('-');
+            TRY(string_builder.try_append('-'));
         else if (sign_mode == SignMode::Always)
-            string_builder.append('+');
+            TRY(string_builder.try_append('+'));
         else if (sign_mode == SignMode::Reserved)
-            string_builder.append(' ');
+            TRY(string_builder.try_append(' '));
 
         if (isnan(value))
-            string_builder.append(upper_case ? "NAN"sv : "nan"sv);
+            TRY(string_builder.try_append(upper_case ? "NAN"sv : "nan"sv));
         else
-            string_builder.append(upper_case ? "INF"sv : "inf"sv);
-        put_string(string_builder.string_view(), align, min_width, NumericLimits<size_t>::max(), fill);
-        return;
+            TRY(string_builder.try_append(upper_case ? "INF"sv : "inf"sv));
+        TRY(put_string(string_builder.string_view(), align, min_width, NumericLimits<size_t>::max(), fill));
+        return {};
     }
 
     bool is_negative = value < 0.0l;
     if (is_negative)
         value = -value;
 
-    format_builder.put_u64(static_cast<u64>(value), base, false, upper_case, false, Align::Right, 0, ' ', sign_mode, is_negative);
+    TRY(format_builder.put_u64(static_cast<u64>(value), base, false, upper_case, false, Align::Right, 0, ' ', sign_mode, is_negative));
 
     if (precision > 0) {
         // FIXME: This is a terrible approximation but doing it properly would be a lot of work. If someone is up for that, a good
@@ -468,44 +480,50 @@ void FormatBuilder::put_f80(
 
         if (visible_precision > 0) {
             string_builder.append('.');
-            format_builder.put_u64(static_cast<u64>(value), base, false, upper_case, true, Align::Right, visible_precision);
+            TRY(format_builder.put_u64(static_cast<u64>(value), base, false, upper_case, true, Align::Right, visible_precision));
         }
     }
 
-    put_string(string_builder.string_view(), align, min_width, NumericLimits<size_t>::max(), fill);
+    TRY(put_string(string_builder.string_view(), align, min_width, NumericLimits<size_t>::max(), fill));
+    return {};
 }
 
 #endif
 
-void FormatBuilder::put_hexdump(ReadonlyBytes bytes, size_t width, char fill)
+ErrorOr<void> FormatBuilder::put_hexdump(ReadonlyBytes bytes, size_t width, char fill)
 {
-    auto put_char_view = [&](auto i) {
-        put_padding(fill, 4);
+    auto put_char_view = [&](auto i) -> ErrorOr<void> {
+        TRY(put_padding(fill, 4));
         for (size_t j = i - width; j < i; ++j) {
             auto ch = bytes[j];
-            m_builder.append(ch >= 32 && ch <= 127 ? ch : '.'); // silly hack
+            TRY(m_builder.try_append(ch >= 32 && ch <= 127 ? ch : '.')); // silly hack
         }
+        return {};
     };
+
     for (size_t i = 0; i < bytes.size(); ++i) {
         if (width > 0) {
             if (i % width == 0 && i) {
-                put_char_view(i);
-                put_literal("\n"sv);
+                TRY(put_char_view(i));
+                TRY(put_literal("\n"sv));
             }
         }
-        put_u64(bytes[i], 16, false, false, true, Align::Right, 2);
+        TRY(put_u64(bytes[i], 16, false, false, true, Align::Right, 2));
     }
 
     if (width > 0 && bytes.size() && bytes.size() % width == 0)
-        put_char_view(bytes.size());
+        TRY(put_char_view(bytes.size()));
+
+    return {};
 }
 
-void vformat(StringBuilder& builder, StringView fmtstr, TypeErasedFormatParams& params)
+ErrorOr<void> vformat(StringBuilder& builder, StringView fmtstr, TypeErasedFormatParams& params)
 {
     FormatBuilder fmtbuilder { builder };
     FormatParser parser { fmtstr };
 
-    vformat_impl(params, fmtbuilder, parser);
+    TRY(vformat_impl(params, fmtbuilder, parser));
+    return {};
 }
 
 void StandardFormatter::parse(TypeErasedFormatParams& params, FormatParser& parser)
@@ -588,7 +606,7 @@ void StandardFormatter::parse(TypeErasedFormatParams& params, FormatParser& pars
     VERIFY(parser.is_eof());
 }
 
-void Formatter<StringView>::format(FormatBuilder& builder, StringView value)
+ErrorOr<void> Formatter<StringView>::format(FormatBuilder& builder, StringView value)
 {
     if (m_sign_mode != FormatBuilder::SignMode::Default)
         VERIFY_NOT_REACHED();
@@ -603,20 +621,20 @@ void Formatter<StringView>::format(FormatBuilder& builder, StringView value)
     m_precision = m_precision.value_or(NumericLimits<size_t>::max());
 
     if (m_mode == Mode::HexDump)
-        builder.put_hexdump(value.bytes(), m_width.value(), m_fill);
-    else
-        builder.put_string(value, m_align, m_width.value(), m_precision.value(), m_fill);
+        return builder.put_hexdump(value.bytes(), m_width.value(), m_fill);
+    return builder.put_string(value, m_align, m_width.value(), m_precision.value(), m_fill);
 }
 
-void Formatter<FormatString>::vformat(FormatBuilder& builder, StringView fmtstr, TypeErasedFormatParams& params)
+ErrorOr<void> Formatter<FormatString>::vformat(FormatBuilder& builder, StringView fmtstr, TypeErasedFormatParams& params)
 {
     StringBuilder string_builder;
-    AK::vformat(string_builder, fmtstr, params);
-    return Formatter<StringView>::format(builder, string_builder.string_view());
+    TRY(AK::vformat(string_builder, fmtstr, params));
+    TRY(Formatter<StringView>::format(builder, string_builder.string_view()));
+    return {};
 }
 
 template<typename T>
-void Formatter<T, typename EnableIf<IsIntegral<T>>::Type>::format(FormatBuilder& builder, T value)
+ErrorOr<void> Formatter<T, typename EnableIf<IsIntegral<T>>::Type>::format(FormatBuilder& builder, T value)
 {
     if (m_mode == Mode::Character) {
         // FIXME: We just support ASCII for now, in the future maybe unicode?
@@ -665,8 +683,7 @@ void Formatter<T, typename EnableIf<IsIntegral<T>>::Type>::format(FormatBuilder&
         upper_case = true;
     } else if (m_mode == Mode::HexDump) {
         m_width = m_width.value_or(32);
-        builder.put_hexdump({ &value, sizeof(value) }, m_width.value(), m_fill);
-        return;
+        return builder.put_hexdump({ &value, sizeof(value) }, m_width.value(), m_fill);
     } else {
         VERIFY_NOT_REACHED();
     }
@@ -674,12 +691,12 @@ void Formatter<T, typename EnableIf<IsIntegral<T>>::Type>::format(FormatBuilder&
     m_width = m_width.value_or(0);
 
     if constexpr (IsSame<MakeUnsigned<T>, T>)
-        builder.put_u64(value, base, m_alternative_form, upper_case, m_zero_pad, m_align, m_width.value(), m_fill, m_sign_mode);
+        return builder.put_u64(value, base, m_alternative_form, upper_case, m_zero_pad, m_align, m_width.value(), m_fill, m_sign_mode);
     else
-        builder.put_i64(value, base, m_alternative_form, upper_case, m_zero_pad, m_align, m_width.value(), m_fill, m_sign_mode);
+        return builder.put_i64(value, base, m_alternative_form, upper_case, m_zero_pad, m_align, m_width.value(), m_fill, m_sign_mode);
 }
 
-void Formatter<char>::format(FormatBuilder& builder, char value)
+ErrorOr<void> Formatter<char>::format(FormatBuilder& builder, char value)
 {
     if (m_mode == Mode::Binary || m_mode == Mode::BinaryUppercase || m_mode == Mode::Decimal || m_mode == Mode::Octal || m_mode == Mode::Hexadecimal || m_mode == Mode::HexadecimalUppercase) {
         // Trick: signed char != char. (Sometimes weird features are actually helpful.)
@@ -690,7 +707,7 @@ void Formatter<char>::format(FormatBuilder& builder, char value)
         return formatter.format(builder, { &value, 1 });
     }
 }
-void Formatter<wchar_t>::format(FormatBuilder& builder, wchar_t value)
+ErrorOr<void> Formatter<wchar_t>::format(FormatBuilder& builder, wchar_t value)
 {
     if (m_mode == Mode::Binary || m_mode == Mode::BinaryUppercase || m_mode == Mode::Decimal || m_mode == Mode::Octal || m_mode == Mode::Hexadecimal || m_mode == Mode::HexadecimalUppercase) {
         Formatter<u32> formatter { *this };
@@ -703,7 +720,7 @@ void Formatter<wchar_t>::format(FormatBuilder& builder, wchar_t value)
         return formatter.format(builder, codepoint.to_string());
     }
 }
-void Formatter<bool>::format(FormatBuilder& builder, bool value)
+ErrorOr<void> Formatter<bool>::format(FormatBuilder& builder, bool value)
 {
     if (m_mode == Mode::Binary || m_mode == Mode::BinaryUppercase || m_mode == Mode::Decimal || m_mode == Mode::Octal || m_mode == Mode::Hexadecimal || m_mode == Mode::HexadecimalUppercase) {
         Formatter<u8> formatter { *this };
@@ -716,7 +733,7 @@ void Formatter<bool>::format(FormatBuilder& builder, bool value)
     }
 }
 #ifndef KERNEL
-void Formatter<long double>::format(FormatBuilder& builder, long double value)
+ErrorOr<void> Formatter<long double>::format(FormatBuilder& builder, long double value)
 {
     u8 base;
     bool upper_case;
@@ -736,10 +753,10 @@ void Formatter<long double>::format(FormatBuilder& builder, long double value)
     m_width = m_width.value_or(0);
     m_precision = m_precision.value_or(6);
 
-    builder.put_f80(value, base, upper_case, m_align, m_width.value(), m_precision.value(), m_fill, m_sign_mode);
+    return builder.put_f80(value, base, upper_case, m_align, m_width.value(), m_precision.value(), m_fill, m_sign_mode);
 }
 
-void Formatter<double>::format(FormatBuilder& builder, double value)
+ErrorOr<void> Formatter<double>::format(FormatBuilder& builder, double value)
 {
     u8 base;
     bool upper_case;
@@ -759,12 +776,13 @@ void Formatter<double>::format(FormatBuilder& builder, double value)
     m_width = m_width.value_or(0);
     m_precision = m_precision.value_or(6);
 
-    builder.put_f64(value, base, upper_case, m_zero_pad, m_align, m_width.value(), m_precision.value(), m_fill, m_sign_mode);
+    return builder.put_f64(value, base, upper_case, m_zero_pad, m_align, m_width.value(), m_precision.value(), m_fill, m_sign_mode);
 }
-void Formatter<float>::format(FormatBuilder& builder, float value)
+
+ErrorOr<void> Formatter<float>::format(FormatBuilder& builder, float value)
 {
     Formatter<double> formatter { *this };
-    formatter.format(builder, value);
+    return formatter.format(builder, value);
 }
 #endif
 
@@ -772,7 +790,7 @@ void Formatter<float>::format(FormatBuilder& builder, float value)
 void vout(FILE* file, StringView fmtstr, TypeErasedFormatParams& params, bool newline)
 {
     StringBuilder builder;
-    vformat(builder, fmtstr, params);
+    MUST(vformat(builder, fmtstr, params));
 
     if (newline)
         builder.append('\n');
@@ -832,7 +850,7 @@ void vdbgln(StringView fmtstr, TypeErasedFormatParams& params)
 #    endif
 #endif
 
-    vformat(builder, fmtstr, params);
+    MUST(vformat(builder, fmtstr, params));
     builder.append('\n');
 
     const auto string = builder.string_view();
@@ -866,7 +884,7 @@ void vdmesgln(StringView fmtstr, TypeErasedFormatParams& params)
     }
 #    endif
 
-    vformat(builder, fmtstr, params);
+    MUST(vformat(builder, fmtstr, params));
     builder.append('\n');
 
     const auto string = builder.string_view();
@@ -888,7 +906,7 @@ void v_critical_dmesgln(StringView fmtstr, TypeErasedFormatParams& params)
     }
 #    endif
 
-    vformat(builder, fmtstr, params);
+    MUST(vformat(builder, fmtstr, params));
     builder.append('\n');
 
     const auto string = builder.string_view();
diff --git a/AK/Format.h b/AK/Format.h
index 37fe5bcc574..e3be0e57050 100644
--- a/AK/Format.h
+++ b/AK/Format.h
@@ -11,6 +11,8 @@
 #include <AK/AllOf.h>
 #include <AK/AnyOf.h>
 #include <AK/Array.h>
+#include <AK/Error.h>
+#include <AK/Forward.h>
 #include <AK/Optional.h>
 #include <AK/StringView.h>
 
@@ -125,7 +127,7 @@ struct TypeErasedParameter {
 
     const void* value;
     Type type;
-    void (*formatter)(TypeErasedFormatParams&, FormatBuilder&, FormatParser&, const void* value);
+    ErrorOr<void> (*formatter)(TypeErasedFormatParams&, FormatBuilder&, FormatParser&, void const* value);
 };
 
 class FormatBuilder {
@@ -148,18 +150,18 @@ public:
     {
     }
 
-    void put_padding(char fill, size_t amount);
+    ErrorOr<void> put_padding(char fill, size_t amount);
 
-    void put_literal(StringView value);
+    ErrorOr<void> put_literal(StringView value);
 
-    void put_string(
+    ErrorOr<void> put_string(
         StringView value,
         Align align = Align::Left,
         size_t min_width = 0,
         size_t max_width = NumericLimits<size_t>::max(),
         char fill = ' ');
 
-    void put_u64(
+    ErrorOr<void> put_u64(
         u64 value,
         u8 base = 10,
         bool prefix = false,
@@ -171,7 +173,7 @@ public:
         SignMode sign_mode = SignMode::OnlyIfNeeded,
         bool is_negative = false);
 
-    void put_i64(
+    ErrorOr<void> put_i64(
         i64 value,
         u8 base = 10,
         bool prefix = false,
@@ -183,7 +185,7 @@ public:
         SignMode sign_mode = SignMode::OnlyIfNeeded);
 
 #ifndef KERNEL
-    void put_f80(
+    ErrorOr<void> put_f80(
         long double value,
         u8 base = 10,
         bool upper_case = false,
@@ -193,7 +195,7 @@ public:
         char fill = ' ',
         SignMode sign_mode = SignMode::OnlyIfNeeded);
 
-    void put_f64(
+    ErrorOr<void> put_f64(
         double value,
         u8 base = 10,
         bool upper_case = false,
@@ -205,7 +207,7 @@ public:
         SignMode sign_mode = SignMode::OnlyIfNeeded);
 #endif
 
-    void put_hexdump(
+    ErrorOr<void> put_hexdump(
         ReadonlyBytes,
         size_t width,
         char fill = ' ');
@@ -233,12 +235,12 @@ private:
 };
 
 template<typename T>
-void __format_value(TypeErasedFormatParams& params, FormatBuilder& builder, FormatParser& parser, const void* value)
+ErrorOr<void> __format_value(TypeErasedFormatParams& params, FormatBuilder& builder, FormatParser& parser, const void* value)
 {
     Formatter<T> formatter;
 
     formatter.parse(params, parser);
-    formatter.format(builder, *static_cast<const T*>(value));
+    return formatter.format(builder, *static_cast<const T*>(value));
 }
 
 template<typename... Parameters>
@@ -298,7 +300,7 @@ struct Formatter<T, typename EnableIf<IsIntegral<T>>::Type> : StandardFormatter
     {
     }
 
-    void format(FormatBuilder&, T value);
+    ErrorOr<void> format(FormatBuilder&, T);
 };
 
 template<>
@@ -309,7 +311,7 @@ struct Formatter<StringView> : StandardFormatter {
     {
     }
 
-    void format(FormatBuilder&, StringView value);
+    ErrorOr<void> format(FormatBuilder&, StringView);
 };
 
 template<typename T>
@@ -320,12 +322,12 @@ requires(HasFormatter<T>) struct Formatter<Vector<T>> : StandardFormatter {
         : StandardFormatter(move(formatter))
     {
     }
-    void format(FormatBuilder& builder, Vector<T> value)
+    ErrorOr<void> format(FormatBuilder& builder, Vector<T> value)
     {
         if (m_mode == Mode::Pointer) {
             Formatter<FlatPtr> formatter { *this };
-            formatter.format(builder, reinterpret_cast<FlatPtr>(value.data()));
-            return;
+            TRY(formatter.format(builder, reinterpret_cast<FlatPtr>(value.data())));
+            return {};
         }
 
         if (m_sign_mode != FormatBuilder::SignMode::Default)
@@ -343,33 +345,34 @@ requires(HasFormatter<T>) struct Formatter<Vector<T>> : StandardFormatter {
         m_precision = m_precision.value_or(NumericLimits<size_t>::max());
 
         Formatter<T> content_fmt;
-        builder.put_literal("[ "sv);
+        TRY(builder.put_literal("[ "sv));
         bool first = true;
         for (auto& content : value) {
             if (!first) {
-                builder.put_literal(", "sv);
+                TRY(builder.put_literal(", "sv));
                 content_fmt = Formatter<T> {};
             }
             first = false;
-            content_fmt.format(builder, content);
+            TRY(content_fmt.format(builder, content));
         }
-        builder.put_literal(" ]"sv);
+        TRY(builder.put_literal(" ]"sv));
+        return {};
     }
 };
 
 template<>
 struct Formatter<ReadonlyBytes> : Formatter<StringView> {
-    void format(FormatBuilder& builder, ReadonlyBytes value)
+    ErrorOr<void> format(FormatBuilder& builder, ReadonlyBytes value)
     {
         if (m_mode == Mode::Pointer) {
             Formatter<FlatPtr> formatter { *this };
-            formatter.format(builder, reinterpret_cast<FlatPtr>(value.data()));
-        } else if (m_mode == Mode::Default || m_mode == Mode::HexDump) {
-            m_mode = Mode::HexDump;
-            Formatter<StringView>::format(builder, value);
-        } else {
-            Formatter<StringView>::format(builder, value);
+            return formatter.format(builder, reinterpret_cast<FlatPtr>(value.data()));
         }
+        if (m_mode == Mode::Default || m_mode == Mode::HexDump) {
+            m_mode = Mode::HexDump;
+            return Formatter<StringView>::format(builder, value);
+        }
+        return Formatter<StringView>::format(builder, value);
     }
 };
 
@@ -379,14 +382,13 @@ struct Formatter<Bytes> : Formatter<ReadonlyBytes> {
 
 template<>
 struct Formatter<const char*> : Formatter<StringView> {
-    void format(FormatBuilder& builder, const char* value)
+    ErrorOr<void> format(FormatBuilder& builder, const char* value)
     {
         if (m_mode == Mode::Pointer) {
             Formatter<FlatPtr> formatter { *this };
-            formatter.format(builder, reinterpret_cast<FlatPtr>(value));
-        } else {
-            Formatter<StringView>::format(builder, value);
+            return formatter.format(builder, reinterpret_cast<FlatPtr>(value));
         }
+        return Formatter<StringView>::format(builder, value);
     }
 };
 template<>
@@ -397,14 +399,13 @@ struct Formatter<char[Size]> : Formatter<const char*> {
 };
 template<size_t Size>
 struct Formatter<unsigned char[Size]> : Formatter<StringView> {
-    void format(FormatBuilder& builder, const unsigned char* value)
+    ErrorOr<void> format(FormatBuilder& builder, const unsigned char* value)
     {
         if (m_mode == Mode::Pointer) {
             Formatter<FlatPtr> formatter { *this };
-            formatter.format(builder, reinterpret_cast<FlatPtr>(value));
-        } else {
-            Formatter<StringView>::format(builder, { value, Size });
+            return formatter.format(builder, reinterpret_cast<FlatPtr>(value));
         }
+        Formatter<StringView>::format(builder, { value, Size });
     }
 };
 template<>
@@ -416,33 +417,33 @@ struct Formatter<FlyString> : Formatter<StringView> {
 
 template<typename T>
 struct Formatter<T*> : StandardFormatter {
-    void format(FormatBuilder& builder, T* value)
+    ErrorOr<void> format(FormatBuilder& builder, T* value)
     {
         if (m_mode == Mode::Default)
             m_mode = Mode::Pointer;
 
         Formatter<FlatPtr> formatter { *this };
-        formatter.format(builder, reinterpret_cast<FlatPtr>(value));
+        return formatter.format(builder, reinterpret_cast<FlatPtr>(value));
     }
 };
 
 template<>
 struct Formatter<char> : StandardFormatter {
-    void format(FormatBuilder&, char value);
+    ErrorOr<void> format(FormatBuilder&, char);
 };
 template<>
 struct Formatter<wchar_t> : StandardFormatter {
-    void format(FormatBuilder& builder, wchar_t value);
+    ErrorOr<void> format(FormatBuilder& builder, wchar_t);
 };
 template<>
 struct Formatter<bool> : StandardFormatter {
-    void format(FormatBuilder&, bool value);
+    ErrorOr<void> format(FormatBuilder&, bool);
 };
 
 #ifndef KERNEL
 template<>
 struct Formatter<float> : StandardFormatter {
-    void format(FormatBuilder&, float value);
+    ErrorOr<void> format(FormatBuilder&, float value);
 };
 template<>
 struct Formatter<double> : StandardFormatter {
@@ -452,7 +453,7 @@ struct Formatter<double> : StandardFormatter {
     {
     }
 
-    void format(FormatBuilder&, double value);
+    ErrorOr<void> format(FormatBuilder&, double);
 };
 
 template<>
@@ -463,13 +464,13 @@ struct Formatter<long double> : StandardFormatter {
     {
     }
 
-    void format(FormatBuilder&, long double value);
+    ErrorOr<void> format(FormatBuilder&, long double value);
 };
 #endif
 
 template<>
 struct Formatter<std::nullptr_t> : Formatter<FlatPtr> {
-    void format(FormatBuilder& builder, std::nullptr_t)
+    ErrorOr<void> format(FormatBuilder& builder, std::nullptr_t)
     {
         if (m_mode == Mode::Default)
             m_mode = Mode::Pointer;
@@ -478,7 +479,7 @@ struct Formatter<std::nullptr_t> : Formatter<FlatPtr> {
     }
 };
 
-void vformat(StringBuilder&, StringView fmtstr, TypeErasedFormatParams&);
+ErrorOr<void> vformat(StringBuilder&, StringView fmtstr, TypeErasedFormatParams&);
 
 #ifndef KERNEL
 void vout(FILE*, StringView fmtstr, TypeErasedFormatParams&, bool newline = false);
@@ -582,16 +583,16 @@ private:
 };
 template<typename T, bool Supported = false>
 struct __FormatIfSupported : Formatter<StringView> {
-    void format(FormatBuilder& builder, const FormatIfSupported<T>&)
+    ErrorOr<void> format(FormatBuilder& builder, FormatIfSupported<T> const&)
     {
-        Formatter<StringView>::format(builder, "?");
+        return Formatter<StringView>::format(builder, "?");
     }
 };
 template<typename T>
 struct __FormatIfSupported<T, true> : Formatter<T> {
-    void format(FormatBuilder& builder, const FormatIfSupported<T>& value)
+    ErrorOr<void> format(FormatBuilder& builder, FormatIfSupported<T> const& value)
     {
-        Formatter<T>::format(builder, value.value());
+        return Formatter<T>::format(builder, value.value());
     }
 };
 template<typename T>
@@ -605,12 +606,22 @@ struct FormatString {
 template<>
 struct Formatter<FormatString> : Formatter<StringView> {
     template<typename... Parameters>
-    void format(FormatBuilder& builder, StringView fmtstr, const Parameters&... parameters)
+    ErrorOr<void> format(FormatBuilder& builder, StringView fmtstr, const Parameters&... parameters)
     {
         VariadicFormatParams variadic_format_params { parameters... };
-        vformat(builder, fmtstr, variadic_format_params);
+        return vformat(builder, fmtstr, variadic_format_params);
+    }
+    ErrorOr<void> vformat(FormatBuilder& builder, StringView fmtstr, TypeErasedFormatParams& params);
+};
+
+template<>
+struct Formatter<Error> : Formatter<FormatString> {
+    ErrorOr<void> format(FormatBuilder& builder, Error const& error)
+    {
+        if (error.is_errno())
+            return Formatter<FormatString>::format(builder, "Error(errno={})", error.code());
+        return Formatter<FormatString>::format(builder, "Error({})", error.string_literal());
     }
-    void vformat(FormatBuilder& builder, StringView fmtstr, TypeErasedFormatParams& params);
 };
 
 } // namespace AK
diff --git a/AK/IPv4Address.h b/AK/IPv4Address.h
index 3c0f76f6b9e..3df22ea34e4 100644
--- a/AK/IPv4Address.h
+++ b/AK/IPv4Address.h
@@ -133,7 +133,7 @@ struct Traits<IPv4Address> : public GenericTraits<IPv4Address> {
 
 template<>
 struct Formatter<IPv4Address> : Formatter<String> {
-    void format(FormatBuilder& builder, IPv4Address value)
+    ErrorOr<void> format(FormatBuilder& builder, IPv4Address value)
     {
         return Formatter<String>::format(builder, value.to_string());
     }
diff --git a/AK/JsonValue.h b/AK/JsonValue.h
index d4627fb28db..629ba77689d 100644
--- a/AK/JsonValue.h
+++ b/AK/JsonValue.h
@@ -245,9 +245,9 @@ private:
 
 template<>
 struct Formatter<JsonValue> : Formatter<StringView> {
-    void format(FormatBuilder& builder, const JsonValue& value)
+    ErrorOr<void> format(FormatBuilder& builder, JsonValue const& value)
     {
-        Formatter<StringView>::format(builder, value.to_string());
+        return Formatter<StringView>::format(builder, value.to_string());
     }
 };
 
diff --git a/AK/LexicalPath.h b/AK/LexicalPath.h
index 98e11a97c03..d758e9ad199 100644
--- a/AK/LexicalPath.h
+++ b/AK/LexicalPath.h
@@ -81,9 +81,9 @@ private:
 
 template<>
 struct Formatter<LexicalPath> : Formatter<StringView> {
-    void format(FormatBuilder& builder, LexicalPath const& value)
+    ErrorOr<void> format(FormatBuilder& builder, LexicalPath const& value)
     {
-        Formatter<StringView>::format(builder, value.string());
+        return Formatter<StringView>::format(builder, value.string());
     }
 };
 
diff --git a/AK/NonnullOwnPtr.h b/AK/NonnullOwnPtr.h
index 96df3a26f88..1645a0009db 100644
--- a/AK/NonnullOwnPtr.h
+++ b/AK/NonnullOwnPtr.h
@@ -190,9 +190,9 @@ inline void swap(NonnullOwnPtr<T>& a, NonnullOwnPtr<U>& b)
 
 template<typename T>
 struct Formatter<NonnullOwnPtr<T>> : Formatter<const T*> {
-    void format(FormatBuilder& builder, const NonnullOwnPtr<T>& value)
+    ErrorOr<void> format(FormatBuilder& builder, NonnullOwnPtr<T> const& value)
     {
-        Formatter<const T*>::format(builder, value.ptr());
+        return Formatter<const T*>::format(builder, value.ptr());
     }
 };
 
diff --git a/AK/NonnullRefPtr.h b/AK/NonnullRefPtr.h
index e97e5ce5e0f..7f9a0d00c2b 100644
--- a/AK/NonnullRefPtr.h
+++ b/AK/NonnullRefPtr.h
@@ -237,9 +237,9 @@ inline NonnullRefPtr<T> adopt_ref(T& object)
 
 template<typename T>
 struct Formatter<NonnullRefPtr<T>> : Formatter<const T*> {
-    void format(FormatBuilder& builder, const NonnullRefPtr<T>& value)
+    ErrorOr<void> format(FormatBuilder& builder, NonnullRefPtr<T> const& value)
     {
-        Formatter<const T*>::format(builder, value.ptr());
+        return Formatter<const T*>::format(builder, value.ptr());
     }
 };
 
diff --git a/AK/RefPtr.h b/AK/RefPtr.h
index db350b847f9..41fe032d2b4 100644
--- a/AK/RefPtr.h
+++ b/AK/RefPtr.h
@@ -295,9 +295,9 @@ private:
 
 template<typename T>
 struct Formatter<RefPtr<T>> : Formatter<const T*> {
-    void format(FormatBuilder& builder, const RefPtr<T>& value)
+    ErrorOr<void> format(FormatBuilder& builder, RefPtr<T> const& value)
     {
-        Formatter<const T*>::format(builder, value.ptr());
+        return Formatter<const T*>::format(builder, value.ptr());
     }
 };
 
diff --git a/AK/SourceLocation.h b/AK/SourceLocation.h
index cc8260441bb..1fabd378693 100644
--- a/AK/SourceLocation.h
+++ b/AK/SourceLocation.h
@@ -43,7 +43,7 @@ private:
 
 template<>
 struct AK::Formatter<AK::SourceLocation> : AK::Formatter<FormatString> {
-    void format(FormatBuilder& builder, AK::SourceLocation location)
+    ErrorOr<void> format(FormatBuilder& builder, AK::SourceLocation location)
     {
         return AK::Formatter<FormatString>::format(builder, "[{} @ {}:{}]", location.function_name(), location.filename(), location.line_number());
     }
diff --git a/AK/String.cpp b/AK/String.cpp
index a3bb45c5b41..6dec4c14387 100644
--- a/AK/String.cpp
+++ b/AK/String.cpp
@@ -475,7 +475,7 @@ InputStream& operator>>(InputStream& stream, String& string)
 String String::vformatted(StringView fmtstr, TypeErasedFormatParams& params)
 {
     StringBuilder builder;
-    vformat(builder, fmtstr, params);
+    MUST(vformat(builder, fmtstr, params));
     return builder.to_string();
 }
 
diff --git a/AK/StringBuilder.h b/AK/StringBuilder.h
index d154c8be3e8..04fc816db4b 100644
--- a/AK/StringBuilder.h
+++ b/AK/StringBuilder.h
@@ -49,7 +49,7 @@ public:
     void appendff(CheckedFormatString<Parameters...>&& fmtstr, Parameters const&... parameters)
     {
         VariadicFormatParams variadic_format_params { parameters... };
-        vformat(*this, fmtstr.view(), variadic_format_params);
+        MUST(vformat(*this, fmtstr.view(), variadic_format_params));
     }
 
     [[nodiscard]] String build() const;
diff --git a/AK/StringImpl.h b/AK/StringImpl.h
index 079e11825d3..7468924794f 100644
--- a/AK/StringImpl.h
+++ b/AK/StringImpl.h
@@ -109,9 +109,9 @@ inline size_t allocation_size_for_stringimpl(size_t length)
 
 template<>
 struct Formatter<StringImpl> : Formatter<StringView> {
-    void format(FormatBuilder& builder, const StringImpl& value)
+    ErrorOr<void> format(FormatBuilder& builder, StringImpl const& value)
     {
-        Formatter<StringView>::format(builder, { value.characters(), value.length() });
+        return Formatter<StringView>::format(builder, { value.characters(), value.length() });
     }
 };
 
diff --git a/AK/UFixedBigInt.h b/AK/UFixedBigInt.h
index f5302a4b0b7..762a4eb32df 100644
--- a/AK/UFixedBigInt.h
+++ b/AK/UFixedBigInt.h
@@ -714,7 +714,7 @@ struct Formatter<UFixedBigInt<T>> : StandardFormatter {
     {
     }
 
-    void format(FormatBuilder& builder, UFixedBigInt<T> value)
+    ErrorOr<void> format(FormatBuilder& builder, UFixedBigInt<T> value)
     {
         if (m_precision.has_value())
             VERIFY_NOT_REACHED();
@@ -751,12 +751,13 @@ struct Formatter<UFixedBigInt<T>> : StandardFormatter {
         ssize_t lower_length = ceil_div(sizeof(T) * 8, (ssize_t)base);
         Formatter<T> formatter { *this };
         formatter.m_width = max(width - lower_length, (ssize_t)0);
-        formatter.format(builder, value.high());
-        builder.put_literal("'"sv);
+        TRY(formatter.format(builder, value.high()));
+        TRY(builder.put_literal("'"sv));
         formatter.m_zero_pad = true;
         formatter.m_alternative_form = false;
         formatter.m_width = lower_length;
-        formatter.format(builder, value.low());
+        TRY(formatter.format(builder, value.low()));
+        return {};
     }
 };
 }
diff --git a/AK/URL.h b/AK/URL.h
index 031be5b0402..647998df64c 100644
--- a/AK/URL.h
+++ b/AK/URL.h
@@ -147,9 +147,9 @@ private:
 
 template<>
 struct Formatter<URL> : Formatter<StringView> {
-    void format(FormatBuilder& builder, URL const& value)
+    ErrorOr<void> format(FormatBuilder& builder, URL const& value)
     {
-        Formatter<StringView>::format(builder, value.serialize());
+        return Formatter<StringView>::format(builder, value.serialize());
     }
 };
 
diff --git a/AK/Utf16View.h b/AK/Utf16View.h
index 5b6fc24e062..2f293825f9b 100644
--- a/AK/Utf16View.h
+++ b/AK/Utf16View.h
@@ -123,9 +123,9 @@ private:
 
 template<>
 struct AK::Formatter<AK::Utf16View> : Formatter<FormatString> {
-    void format(FormatBuilder& builder, AK::Utf16View const& value)
+    ErrorOr<void> format(FormatBuilder& builder, AK::Utf16View const& value)
     {
-        return builder.builder().append(value);
+        return builder.builder().try_append(value);
     }
 };
 
diff --git a/AK/WeakPtr.h b/AK/WeakPtr.h
index bb3e6bcbb28..69c36d24280 100644
--- a/AK/WeakPtr.h
+++ b/AK/WeakPtr.h
@@ -191,9 +191,9 @@ inline WeakPtr<U> Weakable<T>::make_weak_ptr() const
 
 template<typename T>
 struct Formatter<WeakPtr<T>> : Formatter<const T*> {
-    void format(FormatBuilder& builder, const WeakPtr<T>& value)
+    ErrorOr<void> format(FormatBuilder& builder, WeakPtr<T> const& value)
     {
-        Formatter<const T*>::format(builder, value.ptr());
+        return Formatter<const T*>::format(builder, value.ptr());
     }
 };
 
diff --git a/Kernel/Arch/x86/IO.h b/Kernel/Arch/x86/IO.h
index b42bdce0f79..d53264c22ee 100644
--- a/Kernel/Arch/x86/IO.h
+++ b/Kernel/Arch/x86/IO.h
@@ -143,7 +143,7 @@ private:
 
 template<>
 struct AK::Formatter<IOAddress> : AK::Formatter<FormatString> {
-    void format(FormatBuilder& builder, IOAddress value)
+    ErrorOr<void> format(FormatBuilder& builder, IOAddress value)
     {
         return Formatter<FormatString>::format(builder, "IO {:x}", value.get());
     }
diff --git a/Kernel/Bus/PCI/Definitions.h b/Kernel/Bus/PCI/Definitions.h
index 1118987f4ab..f5630642572 100644
--- a/Kernel/Bus/PCI/Definitions.h
+++ b/Kernel/Bus/PCI/Definitions.h
@@ -298,7 +298,7 @@ class Device;
 
 template<>
 struct AK::Formatter<Kernel::PCI::Address> : Formatter<FormatString> {
-    void format(FormatBuilder& builder, Kernel::PCI::Address value)
+    ErrorOr<void> format(FormatBuilder& builder, Kernel::PCI::Address value)
     {
         return Formatter<FormatString>::format(
             builder,
@@ -308,7 +308,7 @@ struct AK::Formatter<Kernel::PCI::Address> : Formatter<FormatString> {
 
 template<>
 struct AK::Formatter<Kernel::PCI::HardwareID> : Formatter<FormatString> {
-    void format(FormatBuilder& builder, Kernel::PCI::HardwareID value)
+    ErrorOr<void> format(FormatBuilder& builder, Kernel::PCI::HardwareID value)
     {
         return Formatter<FormatString>::format(
             builder,
diff --git a/Kernel/FileSystem/InodeIdentifier.h b/Kernel/FileSystem/InodeIdentifier.h
index 8cee21a3fbf..bd07c7d1cdf 100644
--- a/Kernel/FileSystem/InodeIdentifier.h
+++ b/Kernel/FileSystem/InodeIdentifier.h
@@ -53,7 +53,7 @@ private:
 
 template<>
 struct AK::Formatter<Kernel::InodeIdentifier> : AK::Formatter<FormatString> {
-    void format(FormatBuilder& builder, Kernel::InodeIdentifier value)
+    ErrorOr<void> format(FormatBuilder& builder, Kernel::InodeIdentifier value)
     {
         return AK::Formatter<FormatString>::format(builder, "{}:{}", value.fsid(), value.index());
     }
diff --git a/Kernel/KBufferBuilder.h b/Kernel/KBufferBuilder.h
index e6cded298e1..335096a1d47 100644
--- a/Kernel/KBufferBuilder.h
+++ b/Kernel/KBufferBuilder.h
@@ -37,7 +37,7 @@ public:
         // FIXME: This really not ideal, but vformat expects StringBuilder.
         StringBuilder builder;
         AK::VariadicFormatParams variadic_format_params { parameters... };
-        vformat(builder, fmtstr.view(), variadic_format_params);
+        TRY(vformat(builder, fmtstr.view(), variadic_format_params));
         return append_bytes(builder.string_view().bytes());
     }
 
diff --git a/Kernel/KString.h b/Kernel/KString.h
index d92f400df26..e5ec4d0f79f 100644
--- a/Kernel/KString.h
+++ b/Kernel/KString.h
@@ -46,28 +46,27 @@ namespace AK {
 
 template<>
 struct Formatter<Kernel::KString> : Formatter<StringView> {
-    void format(FormatBuilder& builder, Kernel::KString const& value)
+    ErrorOr<void> format(FormatBuilder& builder, Kernel::KString const& value)
     {
-        Formatter<StringView>::format(builder, value.view());
+        return Formatter<StringView>::format(builder, value.view());
     }
 };
 
 template<>
 struct Formatter<OwnPtr<Kernel::KString>> : Formatter<StringView> {
-    void format(FormatBuilder& builder, OwnPtr<Kernel::KString> const& value)
+    ErrorOr<void> format(FormatBuilder& builder, OwnPtr<Kernel::KString> const& value)
     {
         if (value)
-            Formatter<StringView>::format(builder, value->view());
-        else
-            Formatter<StringView>::format(builder, "[out of memory]"sv);
+            return Formatter<StringView>::format(builder, value->view());
+        return Formatter<StringView>::format(builder, "[out of memory]"sv);
     }
 };
 
 template<>
 struct Formatter<NonnullOwnPtr<Kernel::KString>> : Formatter<StringView> {
-    void format(FormatBuilder& builder, NonnullOwnPtr<Kernel::KString> const& value)
+    ErrorOr<void> format(FormatBuilder& builder, NonnullOwnPtr<Kernel::KString> const& value)
     {
-        Formatter<StringView>::format(builder, value->view());
+        return Formatter<StringView>::format(builder, value->view());
     }
 };
 
diff --git a/Kernel/Library/ThreadSafeNonnullRefPtr.h b/Kernel/Library/ThreadSafeNonnullRefPtr.h
index e12bb05a7fa..0f0a0b0eea9 100644
--- a/Kernel/Library/ThreadSafeNonnullRefPtr.h
+++ b/Kernel/Library/ThreadSafeNonnullRefPtr.h
@@ -322,9 +322,9 @@ inline NonnullRefPtr<T> adopt_ref(T& object)
 
 template<typename T>
 struct Formatter<NonnullRefPtr<T>> : Formatter<const T*> {
-    void format(FormatBuilder& builder, const NonnullRefPtr<T>& value)
+    ErrorOr<void> format(FormatBuilder& builder, const NonnullRefPtr<T>& value)
     {
-        Formatter<const T*>::format(builder, value.ptr());
+        return Formatter<const T*>::format(builder, value.ptr());
     }
 };
 
diff --git a/Kernel/Library/ThreadSafeRefPtr.h b/Kernel/Library/ThreadSafeRefPtr.h
index 0bc3f0eeaef..31f48247805 100644
--- a/Kernel/Library/ThreadSafeRefPtr.h
+++ b/Kernel/Library/ThreadSafeRefPtr.h
@@ -445,9 +445,9 @@ private:
 
 template<typename T>
 struct Formatter<RefPtr<T>> : Formatter<const T*> {
-    void format(FormatBuilder& builder, const RefPtr<T>& value)
+    ErrorOr<void> format(FormatBuilder& builder, RefPtr<T> const& value)
     {
-        Formatter<const T*>::format(builder, value.ptr());
+        return Formatter<const T*>::format(builder, value.ptr());
     }
 };
 
diff --git a/Kernel/Library/ThreadSafeWeakPtr.h b/Kernel/Library/ThreadSafeWeakPtr.h
index b89dc480f29..c5675c57a08 100644
--- a/Kernel/Library/ThreadSafeWeakPtr.h
+++ b/Kernel/Library/ThreadSafeWeakPtr.h
@@ -217,13 +217,13 @@ inline WeakPtr<U> Weakable<T>::make_weak_ptr() const
 
 template<typename T>
 struct Formatter<WeakPtr<T>> : Formatter<const T*> {
-    void format(FormatBuilder& builder, const WeakPtr<T>& value)
+    ErrorOr<void> format(FormatBuilder& builder, WeakPtr<T> const& value)
     {
 #ifdef KERNEL
         auto ref = value.strong_ref();
-        Formatter<const T*>::format(builder, ref.ptr());
+        return Formatter<const T*>::format(builder, ref.ptr());
 #else
-        Formatter<const T*>::format(builder, value.ptr());
+        return Formatter<const T*>::format(builder, value.ptr());
 #endif
     }
 };
diff --git a/Kernel/Memory/VirtualRange.h b/Kernel/Memory/VirtualRange.h
index 93c8f80df3f..fb959f3e52d 100644
--- a/Kernel/Memory/VirtualRange.h
+++ b/Kernel/Memory/VirtualRange.h
@@ -62,7 +62,7 @@ private:
 
 template<>
 struct AK::Formatter<Kernel::Memory::VirtualRange> : Formatter<FormatString> {
-    void format(FormatBuilder& builder, Kernel::Memory::VirtualRange value)
+    ErrorOr<void> format(FormatBuilder& builder, Kernel::Memory::VirtualRange value)
     {
         return Formatter<FormatString>::format(builder, "{} - {} (size {:p})", value.base().as_ptr(), value.base().offset(value.size() - 1).as_ptr(), value.size());
     }
diff --git a/Kernel/PhysicalAddress.h b/Kernel/PhysicalAddress.h
index 195e4c2cc0d..e1f66d6a6aa 100644
--- a/Kernel/PhysicalAddress.h
+++ b/Kernel/PhysicalAddress.h
@@ -58,7 +58,7 @@ private:
 
 template<>
 struct AK::Formatter<PhysicalAddress> : AK::Formatter<FormatString> {
-    void format(FormatBuilder& builder, PhysicalAddress value)
+    ErrorOr<void> format(FormatBuilder& builder, PhysicalAddress value)
     {
         if constexpr (sizeof(PhysicalPtr) == sizeof(u64))
             return AK::Formatter<FormatString>::format(builder, "P{:016x}", value.get());
diff --git a/Kernel/Process.h b/Kernel/Process.h
index e37475a3999..3fe8fe2f55a 100644
--- a/Kernel/Process.h
+++ b/Kernel/Process.h
@@ -980,7 +980,7 @@ inline static ErrorOr<NonnullOwnPtr<KString>> try_copy_kstring_from_user(const K
 
 template<>
 struct AK::Formatter<Kernel::Process> : AK::Formatter<FormatString> {
-    void format(FormatBuilder& builder, const Kernel::Process& value)
+    ErrorOr<void> format(FormatBuilder& builder, Kernel::Process const& value)
     {
         return AK::Formatter<FormatString>::format(builder, "{}({})", value.name(), value.pid().value());
     }
diff --git a/Kernel/Thread.cpp b/Kernel/Thread.cpp
index d24f98b6e6a..45cd0fb34cb 100644
--- a/Kernel/Thread.cpp
+++ b/Kernel/Thread.cpp
@@ -1279,7 +1279,7 @@ void Thread::track_lock_release(LockRank rank)
 
 }
 
-void AK::Formatter<Kernel::Thread>::format(FormatBuilder& builder, const Kernel::Thread& value)
+ErrorOr<void> AK::Formatter<Kernel::Thread>::format(FormatBuilder& builder, Kernel::Thread const& value)
 {
     return AK::Formatter<FormatString>::format(
         builder,
diff --git a/Kernel/Thread.h b/Kernel/Thread.h
index d2b858134d1..5378b2b9bba 100644
--- a/Kernel/Thread.h
+++ b/Kernel/Thread.h
@@ -1432,5 +1432,5 @@ inline IterationDecision Thread::for_each_in_state(State state, Callback callbac
 
 template<>
 struct AK::Formatter<Kernel::Thread> : AK::Formatter<FormatString> {
-    void format(FormatBuilder&, const Kernel::Thread&);
+    ErrorOr<void> format(FormatBuilder&, Kernel::Thread const&);
 };
diff --git a/Kernel/VirtualAddress.h b/Kernel/VirtualAddress.h
index 6f2120389fa..28febf60976 100644
--- a/Kernel/VirtualAddress.h
+++ b/Kernel/VirtualAddress.h
@@ -54,7 +54,7 @@ inline VirtualAddress operator-(const VirtualAddress& a, const VirtualAddress& b
 
 template<>
 struct AK::Formatter<VirtualAddress> : AK::Formatter<FormatString> {
-    void format(FormatBuilder& builder, const VirtualAddress& value)
+    ErrorOr<void> format(FormatBuilder& builder, const VirtualAddress& value)
     {
         return AK::Formatter<FormatString>::format(builder, "V{}", value.as_ptr());
     }
diff --git a/Tests/AK/TestFormat.cpp b/Tests/AK/TestFormat.cpp
index dcae6d3c07f..89324d37aaf 100644
--- a/Tests/AK/TestFormat.cpp
+++ b/Tests/AK/TestFormat.cpp
@@ -201,9 +201,9 @@ struct B {
 };
 template<>
 struct AK::Formatter<B> : Formatter<StringView> {
-    void format(FormatBuilder& builder, B)
+    ErrorOr<void> format(FormatBuilder& builder, B)
     {
-        Formatter<StringView>::format(builder, "B");
+        return Formatter<StringView>::format(builder, "B");
     }
 };
 
@@ -283,7 +283,7 @@ struct C {
 };
 template<>
 struct AK::Formatter<C> : AK::Formatter<FormatString> {
-    void format(FormatBuilder& builder, C c)
+    ErrorOr<void> format(FormatBuilder& builder, C c)
     {
         return AK::Formatter<FormatString>::format(builder, "C(i={})", c.i);
     }
@@ -300,7 +300,7 @@ TEST_CASE(long_long_regression)
 
     StringBuilder builder;
     AK::FormatBuilder fmtbuilder { builder };
-    fmtbuilder.put_i64(0x0123456789abcdefLL);
+    MUST(fmtbuilder.put_i64(0x0123456789abcdefLL));
 
     EXPECT_EQ(builder.string_view(), "81985529216486895");
 }
diff --git a/Tests/LibM/test-math.cpp b/Tests/LibM/test-math.cpp
index 167dedf65c6..35bbab3bbe2 100644
--- a/Tests/LibM/test-math.cpp
+++ b/Tests/LibM/test-math.cpp
@@ -128,15 +128,16 @@ union Extractor {
 namespace AK {
 template<>
 struct Formatter<Extractor> : StandardFormatter {
-    void format(FormatBuilder& builder, const Extractor& value)
+    ErrorOr<void> format(FormatBuilder& builder, Extractor const& value)
     {
-        builder.put_literal("{");
-        builder.put_u64(value.sign);
-        builder.put_literal(", ");
-        builder.put_u64(value.exponent, 16, true);
-        builder.put_literal(", ");
-        builder.put_u64(value.mantissa, 16, true);
-        builder.put_literal("}");
+        TRY(builder.put_literal("{"));
+        TRY(builder.put_u64(value.sign));
+        TRY(builder.put_literal(", "));
+        TRY(builder.put_u64(value.exponent, 16, true));
+        TRY(builder.put_literal(", "));
+        TRY(builder.put_u64(value.mantissa, 16, true));
+        TRY(builder.put_literal("}"));
+        return {};
     }
 };
 }
diff --git a/Userland/DevTools/UserspaceEmulator/ValueWithShadow.h b/Userland/DevTools/UserspaceEmulator/ValueWithShadow.h
index 50e2fb86fbf..db23c2597b0 100644
--- a/Userland/DevTools/UserspaceEmulator/ValueWithShadow.h
+++ b/Userland/DevTools/UserspaceEmulator/ValueWithShadow.h
@@ -172,7 +172,7 @@ inline void ValueAndShadowReference<T>::operator=(const ValueWithShadow<T>& othe
 
 template<typename T>
 struct AK::Formatter<UserspaceEmulator::ValueWithShadow<T>> : AK::Formatter<T> {
-    void format(FormatBuilder& builder, UserspaceEmulator::ValueWithShadow<T> value)
+    ErrorOr<void> format(FormatBuilder& builder, UserspaceEmulator::ValueWithShadow<T> value)
     {
         return Formatter<T>::format(builder, value.value());
     }
diff --git a/Userland/Games/Hearts/Player.h b/Userland/Games/Hearts/Player.h
index 328c5016bc8..2fdc7945fda 100644
--- a/Userland/Games/Hearts/Player.h
+++ b/Userland/Games/Hearts/Player.h
@@ -63,8 +63,8 @@ public:
 
 template<>
 struct AK::Formatter<Hearts::Player> : Formatter<FormatString> {
-    void format(FormatBuilder& builder, Hearts::Player const& player)
+    ErrorOr<void> format(FormatBuilder& builder, Hearts::Player const& player)
     {
-        builder.put_string(player.name);
+        return builder.put_string(player.name);
     }
 };
diff --git a/Userland/Libraries/LibCards/Card.h b/Userland/Libraries/LibCards/Card.h
index fbe0353d9e7..d56b5c71bad 100644
--- a/Userland/Libraries/LibCards/Card.h
+++ b/Userland/Libraries/LibCards/Card.h
@@ -82,7 +82,7 @@ private:
 
 template<>
 struct AK::Formatter<Cards::Card> : Formatter<FormatString> {
-    void format(FormatBuilder& builder, const Cards::Card& card)
+    ErrorOr<void> format(FormatBuilder& builder, Cards::Card const& card)
     {
         StringView type;
 
@@ -103,6 +103,6 @@ struct AK::Formatter<Cards::Card> : Formatter<FormatString> {
             VERIFY_NOT_REACHED();
         }
 
-        Formatter<FormatString>::format(builder, "{:>2}{}", Cards::Card::labels[card.value()], type);
+        return Formatter<FormatString>::format(builder, "{:>2}{}", Cards::Card::labels[card.value()], type);
     }
 };
diff --git a/Userland/Libraries/LibCards/CardStack.h b/Userland/Libraries/LibCards/CardStack.h
index e368d15da75..f79ce183367 100644
--- a/Userland/Libraries/LibCards/CardStack.h
+++ b/Userland/Libraries/LibCards/CardStack.h
@@ -98,7 +98,7 @@ private:
 
 template<>
 struct AK::Formatter<Cards::CardStack> : Formatter<FormatString> {
-    void format(FormatBuilder& builder, const Cards::CardStack& stack)
+    ErrorOr<void> format(FormatBuilder& builder, Cards::CardStack const& stack)
     {
         StringView type;
 
@@ -130,6 +130,6 @@ struct AK::Formatter<Cards::CardStack> : Formatter<FormatString> {
             first_card = false;
         }
 
-        Formatter<FormatString>::format(builder, "{:<10} {:>16}: {}", type, stack.bounding_box(), cards.build());
+        return Formatter<FormatString>::format(builder, "{:<10} {:>16}: {}", type, stack.bounding_box(), cards.build());
     }
 };
diff --git a/Userland/Libraries/LibCore/FileWatcher.h b/Userland/Libraries/LibCore/FileWatcher.h
index 4d94f7f5243..56c21f3978a 100644
--- a/Userland/Libraries/LibCore/FileWatcher.h
+++ b/Userland/Libraries/LibCore/FileWatcher.h
@@ -85,15 +85,15 @@ namespace AK {
 
 template<>
 struct Formatter<Core::FileWatcherEvent> : Formatter<FormatString> {
-    void format(FormatBuilder& builder, const Core::FileWatcherEvent& value)
+    ErrorOr<void> format(FormatBuilder& builder, Core::FileWatcherEvent const& value)
     {
-        Formatter<FormatString>::format(builder, "FileWatcherEvent(\"{}\", {})", value.event_path, value.type);
+        return Formatter<FormatString>::format(builder, "FileWatcherEvent(\"{}\", {})", value.event_path, value.type);
     }
 };
 
 template<>
 struct Formatter<Core::FileWatcherEvent::Type> : Formatter<FormatString> {
-    void format(FormatBuilder& builder, const Core::FileWatcherEvent::Type& value)
+    ErrorOr<void> format(FormatBuilder& builder, Core::FileWatcherEvent::Type const& value)
     {
         char const* type;
         switch (value) {
@@ -116,7 +116,7 @@ struct Formatter<Core::FileWatcherEvent::Type> : Formatter<FormatString> {
             VERIFY_NOT_REACHED();
         }
 
-        builder.put_string(type);
+        return builder.put_string(type);
     }
 };
 
diff --git a/Userland/Libraries/LibCore/Object.h b/Userland/Libraries/LibCore/Object.h
index c5f83ecd9eb..51c35c8e77d 100644
--- a/Userland/Libraries/LibCore/Object.h
+++ b/Userland/Libraries/LibCore/Object.h
@@ -199,7 +199,7 @@ private:
 
 template<>
 struct AK::Formatter<Core::Object> : AK::Formatter<FormatString> {
-    void format(FormatBuilder& builder, const Core::Object& value)
+    ErrorOr<void> format(FormatBuilder& builder, const Core::Object& value)
     {
         return AK::Formatter<FormatString>::format(builder, "{}({})", value.class_name(), &value);
     }
diff --git a/Userland/Libraries/LibCore/SocketAddress.h b/Userland/Libraries/LibCore/SocketAddress.h
index ad6a1f5401d..417d329badf 100644
--- a/Userland/Libraries/LibCore/SocketAddress.h
+++ b/Userland/Libraries/LibCore/SocketAddress.h
@@ -94,7 +94,7 @@ private:
 
 template<>
 struct AK::Formatter<Core::SocketAddress> : Formatter<String> {
-    void format(FormatBuilder& builder, const Core::SocketAddress& value)
+    ErrorOr<void> format(FormatBuilder& builder, Core::SocketAddress const& value)
     {
         return Formatter<String>::format(builder, value.to_string());
     }
diff --git a/Userland/Libraries/LibCrypto/ASN1/DER.cpp b/Userland/Libraries/LibCrypto/ASN1/DER.cpp
index 4952012d54a..76da1a3e9aa 100644
--- a/Userland/Libraries/LibCrypto/ASN1/DER.cpp
+++ b/Userland/Libraries/LibCrypto/ASN1/DER.cpp
@@ -395,7 +395,7 @@ void pretty_print(Decoder& decoder, OutputStream& stream, int indent)
 
 }
 
-void AK::Formatter<Crypto::ASN1::DecodeError>::format(FormatBuilder& fmtbuilder, Crypto::ASN1::DecodeError error)
+ErrorOr<void> AK::Formatter<Crypto::ASN1::DecodeError>::format(FormatBuilder& fmtbuilder, Crypto::ASN1::DecodeError error)
 {
     using Crypto::ASN1::DecodeError;
 
diff --git a/Userland/Libraries/LibCrypto/ASN1/DER.h b/Userland/Libraries/LibCrypto/ASN1/DER.h
index 2b57cd9c197..023b3e22586 100644
--- a/Userland/Libraries/LibCrypto/ASN1/DER.h
+++ b/Userland/Libraries/LibCrypto/ASN1/DER.h
@@ -206,5 +206,5 @@ void pretty_print(Decoder&, OutputStream&, int indent = 0);
 
 template<>
 struct AK::Formatter<Crypto::ASN1::DecodeError> : Formatter<StringView> {
-    void format(FormatBuilder&, Crypto::ASN1::DecodeError);
+    ErrorOr<void> format(FormatBuilder&, Crypto::ASN1::DecodeError);
 };
diff --git a/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp b/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp
index a2c8d77ef7a..48ca0a6050b 100644
--- a/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp
+++ b/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp
@@ -350,14 +350,14 @@ bool UnsignedBigInteger::operator>=(UnsignedBigInteger const& other) const
 
 }
 
-void AK::Formatter<Crypto::UnsignedBigInteger>::format(FormatBuilder& fmtbuilder, const Crypto::UnsignedBigInteger& value)
+ErrorOr<void> AK::Formatter<Crypto::UnsignedBigInteger>::format(FormatBuilder& fmtbuilder, const Crypto::UnsignedBigInteger& value)
 {
     if (value.is_invalid())
         return Formatter<StringView>::format(fmtbuilder, "invalid");
 
     StringBuilder builder;
     for (int i = value.length() - 1; i >= 0; --i)
-        builder.appendff("{}|", value.words()[i]);
+        TRY(builder.try_appendff("{}|", value.words()[i]));
 
     return Formatter<StringView>::format(fmtbuilder, builder.string_view());
 }
diff --git a/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.h b/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.h
index 76c916d0526..5f031b67814 100644
--- a/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.h
+++ b/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.h
@@ -125,7 +125,7 @@ struct UnsignedDivisionResult {
 
 template<>
 struct AK::Formatter<Crypto::UnsignedBigInteger> : Formatter<StringView> {
-    void format(FormatBuilder&, const Crypto::UnsignedBigInteger&);
+    ErrorOr<void> format(FormatBuilder&, Crypto::UnsignedBigInteger const&);
 };
 
 inline Crypto::UnsignedBigInteger
diff --git a/Userland/Libraries/LibDSP/ProcessorParameter.h b/Userland/Libraries/LibDSP/ProcessorParameter.h
index b31ef804cb5..6945a4dd6fa 100644
--- a/Userland/Libraries/LibDSP/ProcessorParameter.h
+++ b/Userland/Libraries/LibDSP/ProcessorParameter.h
@@ -127,12 +127,11 @@ struct AK::Formatter<LibDSP::ProcessorRangeParameter> : AK::StandardFormatter {
         : StandardFormatter(formatter)
     {
     }
-    void format(FormatBuilder& builder, LibDSP::ProcessorRangeParameter value)
+    ErrorOr<void> format(FormatBuilder& builder, LibDSP::ProcessorRangeParameter value)
     {
         if (m_mode == Mode::Pointer) {
             Formatter<FlatPtr> formatter { *this };
-            formatter.format(builder, reinterpret_cast<FlatPtr>(&value));
-            return;
+            return formatter.format(builder, reinterpret_cast<FlatPtr>(&value));
         }
 
         if (m_sign_mode != FormatBuilder::SignMode::Default)
@@ -149,6 +148,7 @@ struct AK::Formatter<LibDSP::ProcessorRangeParameter> : AK::StandardFormatter {
         m_width = m_width.value_or(0);
         m_precision = m_precision.value_or(NumericLimits<size_t>::max());
 
-        builder.put_literal(String::formatted("[{} - {}]: {}", value.min_value(), value.max_value(), value.value()));
+        TRY(builder.put_literal(String::formatted("[{} - {}]: {}", value.min_value(), value.max_value(), value.value())));
+        return {};
     }
 };
diff --git a/Userland/Libraries/LibGUI/ModelIndex.h b/Userland/Libraries/LibGUI/ModelIndex.h
index 6e7141021d4..07743383a5d 100644
--- a/Userland/Libraries/LibGUI/ModelIndex.h
+++ b/Userland/Libraries/LibGUI/ModelIndex.h
@@ -66,12 +66,11 @@ namespace AK {
 
 template<>
 struct Formatter<GUI::ModelIndex> : Formatter<FormatString> {
-    void format(FormatBuilder& builder, const GUI::ModelIndex& value)
+    ErrorOr<void> format(FormatBuilder& builder, GUI::ModelIndex const& value)
     {
         if (value.internal_data())
             return Formatter<FormatString>::format(builder, "ModelIndex({},{},{})", value.row(), value.column(), value.internal_data());
-        else
-            return Formatter<FormatString>::format(builder, "ModelIndex({},{})", value.row(), value.column());
+        return Formatter<FormatString>::format(builder, "ModelIndex({},{})", value.row(), value.column());
     }
 };
 
diff --git a/Userland/Libraries/LibGUI/PersistentModelIndex.h b/Userland/Libraries/LibGUI/PersistentModelIndex.h
index 1ef3f39fb69..4efa8826421 100644
--- a/Userland/Libraries/LibGUI/PersistentModelIndex.h
+++ b/Userland/Libraries/LibGUI/PersistentModelIndex.h
@@ -73,7 +73,7 @@ namespace AK {
 
 template<>
 struct Formatter<GUI::PersistentModelIndex> : Formatter<FormatString> {
-    void format(FormatBuilder& builder, const GUI::PersistentModelIndex& value)
+    ErrorOr<void> format(FormatBuilder& builder, GUI::PersistentModelIndex const& value)
     {
         return Formatter<FormatString>::format(builder, "PersistentModelIndex({},{},{})", value.row(), value.column(), value.internal_data());
     }
diff --git a/Userland/Libraries/LibGUI/TextPosition.h b/Userland/Libraries/LibGUI/TextPosition.h
index e8621ba1f1c..f650c1c6ca2 100644
--- a/Userland/Libraries/LibGUI/TextPosition.h
+++ b/Userland/Libraries/LibGUI/TextPosition.h
@@ -40,11 +40,11 @@ private:
 
 template<>
 struct AK::Formatter<GUI::TextPosition> : AK::Formatter<FormatString> {
-    void format(FormatBuilder& builder, const GUI::TextPosition& value)
+    ErrorOr<void> format(FormatBuilder& builder, GUI::TextPosition const& value)
     {
         if (value.is_valid())
-            Formatter<FormatString>::format(builder, "({},{})", value.line(), value.column());
-        else
-            Formatter<FormatString>::format(builder, "GUI::TextPosition(Invalid)");
+            return Formatter<FormatString>::format(builder, "({},{})", value.line(), value.column());
+
+        return Formatter<FormatString>::format(builder, "GUI::TextPosition(Invalid)");
     }
 };
diff --git a/Userland/Libraries/LibGUI/TextRange.h b/Userland/Libraries/LibGUI/TextRange.h
index fb372890249..de9f13102cf 100644
--- a/Userland/Libraries/LibGUI/TextRange.h
+++ b/Userland/Libraries/LibGUI/TextRange.h
@@ -68,11 +68,10 @@ private:
 
 template<>
 struct AK::Formatter<GUI::TextRange> : AK::Formatter<FormatString> {
-    void format(FormatBuilder& builder, const GUI::TextRange& value)
+    ErrorOr<void> format(FormatBuilder& builder, GUI::TextRange const& value)
     {
         if (value.is_valid())
             return Formatter<FormatString>::format(builder, "{}-{}", value.start(), value.end());
-        else
-            return Formatter<FormatString>::format(builder, "GUI::TextRange(Invalid)");
+        return Formatter<FormatString>::format(builder, "GUI::TextRange(Invalid)");
     }
 };
diff --git a/Userland/Libraries/LibGfx/AffineTransform.h b/Userland/Libraries/LibGfx/AffineTransform.h
index 63277b10490..1ec3ace816d 100644
--- a/Userland/Libraries/LibGfx/AffineTransform.h
+++ b/Userland/Libraries/LibGfx/AffineTransform.h
@@ -70,7 +70,7 @@ private:
 
 template<>
 struct AK::Formatter<Gfx::AffineTransform> : Formatter<FormatString> {
-    void format(FormatBuilder& builder, Gfx::AffineTransform value)
+    ErrorOr<void> format(FormatBuilder& builder, Gfx::AffineTransform const& value)
     {
         return Formatter<FormatString>::format(builder, "[{} {} {} {} {} {}]", value.a(), value.b(), value.c(), value.d(), value.e(), value.f());
     }
diff --git a/Userland/Libraries/LibGfx/BMPLoader.cpp b/Userland/Libraries/LibGfx/BMPLoader.cpp
index f8056a0596b..d96512fec0f 100644
--- a/Userland/Libraries/LibGfx/BMPLoader.cpp
+++ b/Userland/Libraries/LibGfx/BMPLoader.cpp
@@ -75,9 +75,9 @@ namespace AK {
 
 template<typename T>
 struct Formatter<Gfx::Endpoint<T>> : Formatter<StringView> {
-    void format(FormatBuilder& builder, const Gfx::Endpoint<T>& value)
+    ErrorOr<void> format(FormatBuilder& builder, Gfx::Endpoint<T> const& value)
     {
-        Formatter<StringView>::format(builder, String::formatted("({}, {}, {})", value.x, value.y, value.z));
+        return Formatter<StringView>::format(builder, String::formatted("({}, {}, {})", value.x, value.y, value.z));
     }
 };
 
diff --git a/Userland/Libraries/LibGfx/Color.cpp b/Userland/Libraries/LibGfx/Color.cpp
index 92fd42c0b6b..30bb560a72b 100644
--- a/Userland/Libraries/LibGfx/Color.cpp
+++ b/Userland/Libraries/LibGfx/Color.cpp
@@ -352,7 +352,7 @@ bool IPC::decode(IPC::Decoder& decoder, Color& color)
     return true;
 }
 
-void AK::Formatter<Gfx::Color>::format(FormatBuilder& builder, Gfx::Color const& value)
+ErrorOr<void> AK::Formatter<Gfx::Color>::format(FormatBuilder& builder, Gfx::Color const& value)
 {
-    Formatter<StringView>::format(builder, value.to_string());
+    return Formatter<StringView>::format(builder, value.to_string());
 }
diff --git a/Userland/Libraries/LibGfx/Color.h b/Userland/Libraries/LibGfx/Color.h
index 1c217415686..860c12f0335 100644
--- a/Userland/Libraries/LibGfx/Color.h
+++ b/Userland/Libraries/LibGfx/Color.h
@@ -478,7 +478,7 @@ namespace AK {
 
 template<>
 struct Formatter<Gfx::Color> : public Formatter<StringView> {
-    void format(FormatBuilder& builder, Gfx::Color const& value);
+    ErrorOr<void> format(FormatBuilder&, Gfx::Color const&);
 };
 
 }
diff --git a/Userland/Libraries/LibGfx/Point.h b/Userland/Libraries/LibGfx/Point.h
index 88afb4147d6..809a504a437 100644
--- a/Userland/Libraries/LibGfx/Point.h
+++ b/Userland/Libraries/LibGfx/Point.h
@@ -280,9 +280,9 @@ namespace AK {
 
 template<typename T>
 struct Formatter<Gfx::Point<T>> : Formatter<StringView> {
-    void format(FormatBuilder& builder, Gfx::Point<T> const& value)
+    ErrorOr<void> format(FormatBuilder& builder, Gfx::Point<T> const& value)
     {
-        Formatter<StringView>::format(builder, value.to_string());
+        return Formatter<StringView>::format(builder, value.to_string());
     }
 };
 
diff --git a/Userland/Libraries/LibGfx/Rect.h b/Userland/Libraries/LibGfx/Rect.h
index ab9370ffce4..ef61e965b84 100644
--- a/Userland/Libraries/LibGfx/Rect.h
+++ b/Userland/Libraries/LibGfx/Rect.h
@@ -726,9 +726,9 @@ namespace AK {
 
 template<typename T>
 struct Formatter<Gfx::Rect<T>> : Formatter<StringView> {
-    void format(FormatBuilder& builder, const Gfx::Rect<T>& value)
+    ErrorOr<void> format(FormatBuilder& builder, Gfx::Rect<T> const& value)
     {
-        Formatter<StringView>::format(builder, value.to_string());
+        return Formatter<StringView>::format(builder, value.to_string());
     }
 };
 
diff --git a/Userland/Libraries/LibGfx/Size.h b/Userland/Libraries/LibGfx/Size.h
index 66814a11371..52e3ac514e5 100644
--- a/Userland/Libraries/LibGfx/Size.h
+++ b/Userland/Libraries/LibGfx/Size.h
@@ -178,9 +178,9 @@ namespace AK {
 
 template<typename T>
 struct Formatter<Gfx::Size<T>> : Formatter<StringView> {
-    void format(FormatBuilder& builder, Gfx::Size<T> const& value)
+    ErrorOr<void> format(FormatBuilder& builder, Gfx::Size<T> const& value)
     {
-        Formatter<StringView>::format(builder, value.to_string());
+        return Formatter<StringView>::format(builder, value.to_string());
     }
 };
 
diff --git a/Userland/Libraries/LibGfx/Vector2.h b/Userland/Libraries/LibGfx/Vector2.h
index 92c8043ff4f..1868e8f8aad 100644
--- a/Userland/Libraries/LibGfx/Vector2.h
+++ b/Userland/Libraries/LibGfx/Vector2.h
@@ -127,9 +127,9 @@ namespace AK {
 
 template<typename T>
 struct Formatter<Gfx::Vector2<T>> : Formatter<StringView> {
-    void format(FormatBuilder& builder, const Gfx::Vector2<T>& value)
+    ErrorOr<void> format(FormatBuilder& builder, Gfx::Vector2<T> const& value)
     {
-        Formatter<StringView>::format(builder, value.to_string());
+        return Formatter<StringView>::format(builder, value.to_string());
     }
 };
 
diff --git a/Userland/Libraries/LibGfx/Vector3.h b/Userland/Libraries/LibGfx/Vector3.h
index 0e17d2721e9..c6485eecb55 100644
--- a/Userland/Libraries/LibGfx/Vector3.h
+++ b/Userland/Libraries/LibGfx/Vector3.h
@@ -144,9 +144,9 @@ namespace AK {
 
 template<typename T>
 struct Formatter<Gfx::Vector3<T>> : Formatter<StringView> {
-    void format(FormatBuilder& builder, const Gfx::Vector3<T>& value)
+    ErrorOr<void> format(FormatBuilder& builder, Gfx::Vector3<T> const& value)
     {
-        Formatter<StringView>::format(builder, value.to_string());
+        return Formatter<StringView>::format(builder, value.to_string());
     }
 };
 
diff --git a/Userland/Libraries/LibGfx/Vector4.h b/Userland/Libraries/LibGfx/Vector4.h
index 7745af60f46..53e9c7bc148 100644
--- a/Userland/Libraries/LibGfx/Vector4.h
+++ b/Userland/Libraries/LibGfx/Vector4.h
@@ -145,9 +145,9 @@ namespace AK {
 
 template<typename T>
 struct Formatter<Gfx::Vector4<T>> : Formatter<StringView> {
-    void format(FormatBuilder& builder, const Gfx::Vector4<T>& value)
+    ErrorOr<void> format(FormatBuilder& builder, Gfx::Vector4<T> const& value)
     {
-        Formatter<StringView>::format(builder, value.to_string());
+        return Formatter<StringView>::format(builder, value.to_string());
     }
 };
 
diff --git a/Userland/Libraries/LibJS/Bytecode/Label.h b/Userland/Libraries/LibJS/Bytecode/Label.h
index b1634b1d0d6..a858ef0fc02 100644
--- a/Userland/Libraries/LibJS/Bytecode/Label.h
+++ b/Userland/Libraries/LibJS/Bytecode/Label.h
@@ -28,7 +28,7 @@ private:
 
 template<>
 struct AK::Formatter<JS::Bytecode::Label> : AK::Formatter<FormatString> {
-    void format(FormatBuilder& builder, JS::Bytecode::Label const& value)
+    ErrorOr<void> format(FormatBuilder& builder, JS::Bytecode::Label const& value)
     {
         return AK::Formatter<FormatString>::format(builder, "@{}", value.block().name());
     }
diff --git a/Userland/Libraries/LibJS/Bytecode/Register.h b/Userland/Libraries/LibJS/Bytecode/Register.h
index 1de1826c3ad..aeae630f3dc 100644
--- a/Userland/Libraries/LibJS/Bytecode/Register.h
+++ b/Userland/Libraries/LibJS/Bytecode/Register.h
@@ -42,7 +42,7 @@ private:
 
 template<>
 struct AK::Formatter<JS::Bytecode::Register> : AK::Formatter<FormatString> {
-    void format(FormatBuilder& builder, JS::Bytecode::Register const& value)
+    ErrorOr<void> format(FormatBuilder& builder, JS::Bytecode::Register const& value)
     {
         if (value.index() == JS::Bytecode::Register::accumulator_index)
             return AK::Formatter<FormatString>::format(builder, "acc");
diff --git a/Userland/Libraries/LibJS/Heap/Cell.h b/Userland/Libraries/LibJS/Heap/Cell.h
index 85bc0e56752..4e6701e6cae 100644
--- a/Userland/Libraries/LibJS/Heap/Cell.h
+++ b/Userland/Libraries/LibJS/Heap/Cell.h
@@ -75,11 +75,11 @@ private:
 
 template<>
 struct AK::Formatter<JS::Cell> : AK::Formatter<FormatString> {
-    void format(FormatBuilder& builder, const JS::Cell* cell)
+    ErrorOr<void> format(FormatBuilder& builder, JS::Cell const* cell)
     {
         if (!cell)
-            Formatter<FormatString>::format(builder, "Cell{nullptr}");
+            return Formatter<FormatString>::format(builder, "Cell{nullptr}");
         else
-            Formatter<FormatString>::format(builder, "{}({})", cell->class_name(), cell);
+            return Formatter<FormatString>::format(builder, "{}({})", cell->class_name(), cell);
     }
 };
diff --git a/Userland/Libraries/LibJS/Runtime/PropertyAttributes.h b/Userland/Libraries/LibJS/Runtime/PropertyAttributes.h
index a31b0e048f2..f00020246a5 100644
--- a/Userland/Libraries/LibJS/Runtime/PropertyAttributes.h
+++ b/Userland/Libraries/LibJS/Runtime/PropertyAttributes.h
@@ -75,13 +75,13 @@ namespace AK {
 
 template<>
 struct Formatter<JS::PropertyAttributes> : Formatter<StringView> {
-    void format(FormatBuilder& builder, JS::PropertyAttributes const& property_attributes)
+    ErrorOr<void> format(FormatBuilder& builder, JS::PropertyAttributes const& property_attributes)
     {
         Vector<String> parts;
         parts.append(String::formatted("[[Writable]]: {}", property_attributes.is_writable()));
         parts.append(String::formatted("[[Enumerable]]: {}", property_attributes.is_enumerable()));
         parts.append(String::formatted("[[Configurable]]: {}", property_attributes.is_configurable()));
-        Formatter<StringView>::format(builder, String::formatted("PropertyAttributes {{ {} }}", String::join(", ", parts)));
+        return Formatter<StringView>::format(builder, String::formatted("PropertyAttributes {{ {} }}", String::join(", ", parts)));
     }
 };
 
diff --git a/Userland/Libraries/LibJS/Runtime/PropertyDescriptor.h b/Userland/Libraries/LibJS/Runtime/PropertyDescriptor.h
index 4a3b5fbbb74..2fd209147d3 100644
--- a/Userland/Libraries/LibJS/Runtime/PropertyDescriptor.h
+++ b/Userland/Libraries/LibJS/Runtime/PropertyDescriptor.h
@@ -47,7 +47,7 @@ namespace AK {
 
 template<>
 struct Formatter<JS::PropertyDescriptor> : Formatter<StringView> {
-    void format(FormatBuilder& builder, JS::PropertyDescriptor const& property_descriptor)
+    ErrorOr<void> format(FormatBuilder& builder, JS::PropertyDescriptor const& property_descriptor)
     {
         Vector<String> parts;
         if (property_descriptor.value.has_value())
@@ -62,7 +62,7 @@ struct Formatter<JS::PropertyDescriptor> : Formatter<StringView> {
             parts.append(String::formatted("[[Enumerable]]: {}", *property_descriptor.enumerable));
         if (property_descriptor.configurable.has_value())
             parts.append(String::formatted("[[Configurable]]: {}", *property_descriptor.configurable));
-        Formatter<StringView>::format(builder, String::formatted("PropertyDescriptor {{ {} }}", String::join(", ", parts)));
+        return Formatter<StringView>::format(builder, String::formatted("PropertyDescriptor {{ {} }}", String::join(", ", parts)));
     }
 };
 
diff --git a/Userland/Libraries/LibJS/Runtime/PropertyKey.h b/Userland/Libraries/LibJS/Runtime/PropertyKey.h
index b6eb92505ca..f74cf56bc2a 100644
--- a/Userland/Libraries/LibJS/Runtime/PropertyKey.h
+++ b/Userland/Libraries/LibJS/Runtime/PropertyKey.h
@@ -225,14 +225,13 @@ struct Traits<JS::PropertyKey> : public GenericTraits<JS::PropertyKey> {
 
 template<>
 struct Formatter<JS::PropertyKey> : Formatter<StringView> {
-    void format(FormatBuilder& builder, JS::PropertyKey const& property_name)
+    ErrorOr<void> format(FormatBuilder& builder, JS::PropertyKey const& property_name)
     {
         if (!property_name.is_valid())
-            Formatter<StringView>::format(builder, "<invalid PropertyKey>");
-        else if (property_name.is_number())
-            Formatter<StringView>::format(builder, String::number(property_name.as_number()));
-        else
-            Formatter<StringView>::format(builder, property_name.to_string_or_symbol().to_display_string());
+            return Formatter<StringView>::format(builder, "<invalid PropertyKey>");
+        if (property_name.is_number())
+            return Formatter<StringView>::format(builder, String::number(property_name.as_number()));
+        return Formatter<StringView>::format(builder, property_name.to_string_or_symbol().to_display_string());
     }
 };
 
diff --git a/Userland/Libraries/LibJS/Runtime/Value.h b/Userland/Libraries/LibJS/Runtime/Value.h
index 4a29327dd0e..52e7dd2c437 100644
--- a/Userland/Libraries/LibJS/Runtime/Value.h
+++ b/Userland/Libraries/LibJS/Runtime/Value.h
@@ -458,9 +458,9 @@ namespace AK {
 
 template<>
 struct Formatter<JS::Value> : Formatter<StringView> {
-    void format(FormatBuilder& builder, const JS::Value& value)
+    ErrorOr<void> format(FormatBuilder& builder, JS::Value value)
     {
-        Formatter<StringView>::format(builder, value.is_empty() ? "<empty>" : value.to_string_without_side_effects());
+        return Formatter<StringView>::format(builder, value.is_empty() ? "<empty>" : value.to_string_without_side_effects());
     }
 };
 
diff --git a/Userland/Libraries/LibPDF/Command.h b/Userland/Libraries/LibPDF/Command.h
index 01f69aedc07..3f9572c742b 100644
--- a/Userland/Libraries/LibPDF/Command.h
+++ b/Userland/Libraries/LibPDF/Command.h
@@ -166,7 +166,7 @@ namespace AK {
 
 template<>
 struct Formatter<PDF::Command> : Formatter<StringView> {
-    void format(FormatBuilder& format_builder, PDF::Command const& command)
+    ErrorOr<void> format(FormatBuilder& format_builder, PDF::Command const& command)
     {
         StringBuilder builder;
         builder.appendff("{} ({})",
@@ -180,7 +180,7 @@ struct Formatter<PDF::Command> : Formatter<StringView> {
             builder.append(" ]");
         }
 
-        Formatter<StringView>::format(format_builder, builder.to_string());
+        return Formatter<StringView>::format(format_builder, builder.to_string());
     }
 };
 
diff --git a/Userland/Libraries/LibPDF/Document.h b/Userland/Libraries/LibPDF/Document.h
index ddd26443cdc..02303cee02a 100644
--- a/Userland/Libraries/LibPDF/Document.h
+++ b/Userland/Libraries/LibPDF/Document.h
@@ -143,9 +143,9 @@ namespace AK {
 
 template<>
 struct Formatter<PDF::Rectangle> : Formatter<StringView> {
-    void format(FormatBuilder& builder, PDF::Rectangle const& rectangle)
+    ErrorOr<void> format(FormatBuilder& builder, PDF::Rectangle const& rectangle)
     {
-        Formatter<StringView>::format(builder,
+        return Formatter<StringView>::format(builder,
             String::formatted("Rectangle {{ ll=({}, {}), ur=({}, {}) }}",
                 rectangle.lower_left_x,
                 rectangle.lower_left_y,
@@ -156,7 +156,7 @@ struct Formatter<PDF::Rectangle> : Formatter<StringView> {
 
 template<>
 struct Formatter<PDF::Page> : Formatter<StringView> {
-    void format(FormatBuilder& builder, PDF::Page const& page)
+    ErrorOr<void> format(FormatBuilder& builder, PDF::Page const& page)
     {
         constexpr auto fmt_string = "Page {{\n  resources={}\n  contents={}\n  media_box={}\n  crop_box={}\n  user_unit={}\n  rotate={}\n}}";
         auto str = String::formatted(fmt_string,
@@ -166,13 +166,13 @@ struct Formatter<PDF::Page> : Formatter<StringView> {
             page.crop_box,
             page.user_unit,
             page.rotate);
-        Formatter<StringView>::format(builder, str);
+        return Formatter<StringView>::format(builder, str);
     }
 };
 
 template<>
 struct Formatter<PDF::Destination> : Formatter<StringView> {
-    void format(FormatBuilder& builder, PDF::Destination const& destination)
+    ErrorOr<void> format(FormatBuilder& builder, PDF::Destination const& destination)
     {
         String type_str;
         switch (destination.type) {
@@ -207,21 +207,21 @@ struct Formatter<PDF::Destination> : Formatter<StringView> {
             param_builder.appendff("{} ", param);
 
         auto str = String::formatted("{{ type={} page={} params={} }}", type_str, destination.page, param_builder.to_string());
-        Formatter<StringView>::format(builder, str);
+        return Formatter<StringView>::format(builder, str);
     }
 };
 
 template<>
 struct Formatter<PDF::OutlineItem> : Formatter<StringView> {
-    void format(FormatBuilder& builder, PDF::OutlineItem const& item)
+    ErrorOr<void> format(FormatBuilder& builder, PDF::OutlineItem const& item)
     {
-        Formatter<StringView>::format(builder, item.to_string(0));
+        return Formatter<StringView>::format(builder, item.to_string(0));
     }
 };
 
 template<>
 struct Formatter<PDF::OutlineDict> : Formatter<StringView> {
-    void format(FormatBuilder& builder, PDF::OutlineDict const& dict)
+    ErrorOr<void> format(FormatBuilder& builder, PDF::OutlineDict const& dict)
     {
         StringBuilder child_builder;
         child_builder.append('[');
@@ -229,7 +229,7 @@ struct Formatter<PDF::OutlineDict> : Formatter<StringView> {
             child_builder.appendff("{}\n", child.to_string(2));
         child_builder.append("  ]");
 
-        Formatter<StringView>::format(builder,
+        return Formatter<StringView>::format(builder,
             String::formatted("OutlineDict {{\n  count={}\n  children={}\n}}", dict.count, child_builder.to_string()));
     }
 };
diff --git a/Userland/Libraries/LibPDF/Object.h b/Userland/Libraries/LibPDF/Object.h
index f3d0fea884d..5774434ef08 100644
--- a/Userland/Libraries/LibPDF/Object.h
+++ b/Userland/Libraries/LibPDF/Object.h
@@ -63,17 +63,17 @@ namespace AK {
 
 template<PDF::IsObject T>
 struct Formatter<T> : Formatter<StringView> {
-    void format(FormatBuilder& builder, T const& object)
+    ErrorOr<void> format(FormatBuilder& builder, T const& object)
     {
-        Formatter<StringView>::format(builder, object.to_string(0));
+        return Formatter<StringView>::format(builder, object.to_string(0));
     }
 };
 
 template<PDF::IsObject T>
 struct Formatter<NonnullRefPtr<T>> : Formatter<T> {
-    void format(FormatBuilder& builder, NonnullRefPtr<T> const& object)
+    ErrorOr<void> format(FormatBuilder& builder, NonnullRefPtr<T> const& object)
     {
-        Formatter<T>::format(builder, *object);
+        return Formatter<T>::format(builder, *object);
     }
 };
 
diff --git a/Userland/Libraries/LibPDF/Parser.cpp b/Userland/Libraries/LibPDF/Parser.cpp
index 105b5d7f3b9..744a88521ad 100644
--- a/Userland/Libraries/LibPDF/Parser.cpp
+++ b/Userland/Libraries/LibPDF/Parser.cpp
@@ -1187,7 +1187,7 @@ namespace AK {
 
 template<>
 struct Formatter<PDF::Parser::LinearizationDictionary> : Formatter<StringView> {
-    void format(FormatBuilder& format_builder, PDF::Parser::LinearizationDictionary const& dict)
+    ErrorOr<void> format(FormatBuilder& format_builder, PDF::Parser::LinearizationDictionary const& dict)
     {
         StringBuilder builder;
         builder.append("{\n");
@@ -1202,13 +1202,13 @@ struct Formatter<PDF::Parser::LinearizationDictionary> : Formatter<StringView> {
         builder.appendff("  offset_of_main_xref_table={}\n", dict.offset_of_main_xref_table);
         builder.appendff("  first_page={}\n", dict.first_page);
         builder.append('}');
-        Formatter<StringView>::format(format_builder, builder.to_string());
+        return Formatter<StringView>::format(format_builder, builder.to_string());
     }
 };
 
 template<>
 struct Formatter<PDF::Parser::PageOffsetHintTable> : Formatter<StringView> {
-    void format(FormatBuilder& format_builder, PDF::Parser::PageOffsetHintTable const& table)
+    ErrorOr<void> format(FormatBuilder& format_builder, PDF::Parser::PageOffsetHintTable const& table)
     {
         StringBuilder builder;
         builder.append("{\n");
@@ -1226,13 +1226,13 @@ struct Formatter<PDF::Parser::PageOffsetHintTable> : Formatter<StringView> {
         builder.appendff("  bits_required_for_fraction_numerator={}\n", table.bits_required_for_fraction_numerator);
         builder.appendff("  shared_object_reference_fraction_denominator={}\n", table.shared_object_reference_fraction_denominator);
         builder.append('}');
-        Formatter<StringView>::format(format_builder, builder.to_string());
+        return Formatter<StringView>::format(format_builder, builder.to_string());
     }
 };
 
 template<>
 struct Formatter<PDF::Parser::PageOffsetHintTableEntry> : Formatter<StringView> {
-    void format(FormatBuilder& format_builder, PDF::Parser::PageOffsetHintTableEntry const& entry)
+    ErrorOr<void> format(FormatBuilder& format_builder, PDF::Parser::PageOffsetHintTableEntry const& entry)
     {
         StringBuilder builder;
         builder.append("{\n");
@@ -1250,7 +1250,7 @@ struct Formatter<PDF::Parser::PageOffsetHintTableEntry> : Formatter<StringView>
         builder.appendff("  page_content_stream_offset_number={}\n", entry.page_content_stream_offset_number);
         builder.appendff("  page_content_stream_length_number={}\n", entry.page_content_stream_length_number);
         builder.append('}');
-        Formatter<StringView>::format(format_builder, builder.to_string());
+        return Formatter<StringView>::format(format_builder, builder.to_string());
     }
 };
 
diff --git a/Userland/Libraries/LibPDF/Renderer.h b/Userland/Libraries/LibPDF/Renderer.h
index b2daebc19a5..eb8e0f2b631 100644
--- a/Userland/Libraries/LibPDF/Renderer.h
+++ b/Userland/Libraries/LibPDF/Renderer.h
@@ -135,43 +135,37 @@ namespace AK {
 
 template<>
 struct Formatter<PDF::LineCapStyle> : Formatter<StringView> {
-    void format(FormatBuilder& builder, PDF::LineCapStyle const& style)
+    ErrorOr<void> format(FormatBuilder& builder, PDF::LineCapStyle const& style)
     {
         switch (style) {
         case PDF::LineCapStyle::ButtCap:
-            Formatter<StringView>::format(builder, "LineCapStyle::ButtCap");
-            break;
+            return Formatter<StringView>::format(builder, "LineCapStyle::ButtCap");
         case PDF::LineCapStyle::RoundCap:
-            Formatter<StringView>::format(builder, "LineCapStyle::RoundCap");
-            break;
+            return Formatter<StringView>::format(builder, "LineCapStyle::RoundCap");
         case PDF::LineCapStyle::SquareCap:
-            Formatter<StringView>::format(builder, "LineCapStyle::SquareCap");
-            break;
+            return Formatter<StringView>::format(builder, "LineCapStyle::SquareCap");
         }
     }
 };
 
 template<>
 struct Formatter<PDF::LineJoinStyle> : Formatter<StringView> {
-    void format(FormatBuilder& builder, PDF::LineJoinStyle const& style)
+    ErrorOr<void> format(FormatBuilder& builder, PDF::LineJoinStyle const& style)
     {
         switch (style) {
         case PDF::LineJoinStyle::Miter:
-            Formatter<StringView>::format(builder, "LineJoinStyle::Miter");
-            break;
+            return Formatter<StringView>::format(builder, "LineJoinStyle::Miter");
         case PDF::LineJoinStyle::Round:
-            Formatter<StringView>::format(builder, "LineJoinStyle::Round");
-            break;
+            return Formatter<StringView>::format(builder, "LineJoinStyle::Round");
         case PDF::LineJoinStyle::Bevel:
-            Formatter<StringView>::format(builder, "LineJoinStyle::Bevel");
-            break;
+            return Formatter<StringView>::format(builder, "LineJoinStyle::Bevel");
         }
     }
 };
 
 template<>
 struct Formatter<PDF::LineDashPattern> : Formatter<StringView> {
-    void format(FormatBuilder& format_builder, PDF::LineDashPattern const& pattern)
+    ErrorOr<void> format(FormatBuilder& format_builder, PDF::LineDashPattern const& pattern)
     {
         StringBuilder builder;
         builder.append("[");
@@ -191,40 +185,32 @@ struct Formatter<PDF::LineDashPattern> : Formatter<StringView> {
 
 template<>
 struct Formatter<PDF::TextRenderingMode> : Formatter<StringView> {
-    void format(FormatBuilder& builder, PDF::TextRenderingMode const& style)
+    ErrorOr<void> format(FormatBuilder& builder, PDF::TextRenderingMode const& style)
     {
         switch (style) {
         case PDF::TextRenderingMode::Fill:
-            Formatter<StringView>::format(builder, "TextRenderingMode::Fill");
-            break;
+            return Formatter<StringView>::format(builder, "TextRenderingMode::Fill");
         case PDF::TextRenderingMode::Stroke:
-            Formatter<StringView>::format(builder, "TextRenderingMode::Stroke");
-            break;
+            return Formatter<StringView>::format(builder, "TextRenderingMode::Stroke");
         case PDF::TextRenderingMode::FillThenStroke:
-            Formatter<StringView>::format(builder, "TextRenderingMode::FillThenStroke");
-            break;
+            return Formatter<StringView>::format(builder, "TextRenderingMode::FillThenStroke");
         case PDF::TextRenderingMode::Invisible:
-            Formatter<StringView>::format(builder, "TextRenderingMode::Invisible");
-            break;
+            return Formatter<StringView>::format(builder, "TextRenderingMode::Invisible");
         case PDF::TextRenderingMode::FillAndClip:
-            Formatter<StringView>::format(builder, "TextRenderingMode::FillAndClip");
-            break;
+            return Formatter<StringView>::format(builder, "TextRenderingMode::FillAndClip");
         case PDF::TextRenderingMode::StrokeAndClip:
-            Formatter<StringView>::format(builder, "TextRenderingMode::StrokeAndClip");
-            break;
+            return Formatter<StringView>::format(builder, "TextRenderingMode::StrokeAndClip");
         case PDF::TextRenderingMode::FillStrokeAndClip:
-            Formatter<StringView>::format(builder, "TextRenderingMode::FillStrokeAndClip");
-            break;
+            return Formatter<StringView>::format(builder, "TextRenderingMode::FillStrokeAndClip");
         case PDF::TextRenderingMode::Clip:
-            Formatter<StringView>::format(builder, "TextRenderingMode::Clip");
-            break;
+            return Formatter<StringView>::format(builder, "TextRenderingMode::Clip");
         }
     }
 };
 
 template<>
 struct Formatter<PDF::TextState> : Formatter<StringView> {
-    void format(FormatBuilder& format_builder, PDF::TextState const& state)
+    ErrorOr<void> format(FormatBuilder& format_builder, PDF::TextState const& state)
     {
         StringBuilder builder;
         builder.append("TextState {\n");
@@ -239,13 +225,13 @@ struct Formatter<PDF::TextState> : Formatter<StringView> {
         builder.appendff("    rise={}\n", state.rise);
         builder.appendff("    knockout={}\n", state.knockout);
         builder.append(" }");
-        Formatter<StringView>::format(format_builder, builder.to_string());
+        return Formatter<StringView>::format(format_builder, builder.to_string());
     }
 };
 
 template<>
 struct Formatter<PDF::GraphicsState> : Formatter<StringView> {
-    void format(FormatBuilder& format_builder, PDF::GraphicsState const& state)
+    ErrorOr<void> format(FormatBuilder& format_builder, PDF::GraphicsState const& state)
     {
         StringBuilder builder;
         builder.append("GraphicsState {\n");
@@ -259,7 +245,7 @@ struct Formatter<PDF::GraphicsState> : Formatter<StringView> {
         builder.appendff("  line_dash_pattern={}\n", state.line_dash_pattern);
         builder.appendff("  text_state={}\n", state.text_state);
         builder.append("}");
-        Formatter<StringView>::format(format_builder, builder.to_string());
+        return Formatter<StringView>::format(format_builder, builder.to_string());
     }
 };
 
diff --git a/Userland/Libraries/LibPDF/Value.h b/Userland/Libraries/LibPDF/Value.h
index 498fb20d1d3..efce1a30b0b 100644
--- a/Userland/Libraries/LibPDF/Value.h
+++ b/Userland/Libraries/LibPDF/Value.h
@@ -85,9 +85,9 @@ namespace AK {
 
 template<>
 struct Formatter<PDF::Value> : Formatter<StringView> {
-    void format(FormatBuilder& builder, PDF::Value const& value)
+    ErrorOr<void> format(FormatBuilder& builder, PDF::Value const& value)
     {
-        Formatter<StringView>::format(builder, value.to_string());
+        return Formatter<StringView>::format(builder, value.to_string());
     }
 };
 
diff --git a/Userland/Libraries/LibPDF/XRefTable.h b/Userland/Libraries/LibPDF/XRefTable.h
index 5ac0cd355f0..efb87f23147 100644
--- a/Userland/Libraries/LibPDF/XRefTable.h
+++ b/Userland/Libraries/LibPDF/XRefTable.h
@@ -101,9 +101,9 @@ namespace AK {
 
 template<>
 struct Formatter<PDF::XRefEntry> : Formatter<StringView> {
-    void format(FormatBuilder& builder, PDF::XRefEntry const& entry)
+    ErrorOr<void> format(FormatBuilder& builder, PDF::XRefEntry const& entry)
     {
-        Formatter<StringView>::format(builder,
+        return Formatter<StringView>::format(builder,
             String::formatted("XRefEntry {{ offset={} generation={} used={} }}",
                 entry.byte_offset,
                 entry.generation_number,
@@ -113,14 +113,14 @@ struct Formatter<PDF::XRefEntry> : Formatter<StringView> {
 
 template<>
 struct Formatter<PDF::XRefTable> : Formatter<StringView> {
-    void format(FormatBuilder& format_builder, PDF::XRefTable const& table)
+    ErrorOr<void> format(FormatBuilder& format_builder, PDF::XRefTable const& table)
     {
         StringBuilder builder;
         builder.append("XRefTable {");
         for (auto& entry : table.m_entries)
             builder.appendff("\n  {}", entry);
         builder.append("\n}");
-        Formatter<StringView>::format(format_builder, builder.to_string());
+        return Formatter<StringView>::format(format_builder, builder.to_string());
     }
 };
 
diff --git a/Userland/Libraries/LibRegex/RegexMatch.h b/Userland/Libraries/LibRegex/RegexMatch.h
index 2ebd0f5f8c0..201b98e0660 100644
--- a/Userland/Libraries/LibRegex/RegexMatch.h
+++ b/Userland/Libraries/LibRegex/RegexMatch.h
@@ -536,7 +536,7 @@ using regex::RegexStringView;
 
 template<>
 struct AK::Formatter<regex::RegexStringView> : Formatter<StringView> {
-    void format(FormatBuilder& builder, regex::RegexStringView value)
+    ErrorOr<void> format(FormatBuilder& builder, regex::RegexStringView value)
     {
         auto string = value.to_string();
         return Formatter<StringView>::format(builder, string);
diff --git a/Userland/Libraries/LibWasm/AbstractMachine/Validator.h b/Userland/Libraries/LibWasm/AbstractMachine/Validator.h
index e4f8b928ef1..4e8010f98f4 100644
--- a/Userland/Libraries/LibWasm/AbstractMachine/Validator.h
+++ b/Userland/Libraries/LibWasm/AbstractMachine/Validator.h
@@ -286,27 +286,27 @@ private:
 
 template<>
 struct AK::Formatter<Wasm::Validator::StackEntry> : public AK::Formatter<StringView> {
-    void format(FormatBuilder& builder, Wasm::Validator::StackEntry const& value)
+    ErrorOr<void> format(FormatBuilder& builder, Wasm::Validator::StackEntry const& value)
     {
         if (value.is_known)
             return Formatter<StringView>::format(builder, Wasm::ValueType::kind_name(value.concrete_type.kind()));
 
-        Formatter<StringView>::format(builder, "<unknown>"sv);
+        return Formatter<StringView>::format(builder, "<unknown>"sv);
     }
 };
 
 template<>
 struct AK::Formatter<Wasm::ValueType> : public AK::Formatter<StringView> {
-    void format(FormatBuilder& builder, Wasm::ValueType const& value)
+    ErrorOr<void> format(FormatBuilder& builder, Wasm::ValueType const& value)
     {
-        Formatter<StringView>::format(builder, Wasm::ValueType::kind_name(value.kind()));
+        return Formatter<StringView>::format(builder, Wasm::ValueType::kind_name(value.kind()));
     }
 };
 
 template<>
 struct AK::Formatter<Wasm::ValidationError> : public AK::Formatter<StringView> {
-    void format(FormatBuilder& builder, Wasm::ValidationError const& error)
+    ErrorOr<void> format(FormatBuilder& builder, Wasm::ValidationError const& error)
     {
-        Formatter<StringView>::format(builder, error.error_string);
+        return Formatter<StringView>::format(builder, error.error_string);
     }
 };
diff --git a/Userland/Libraries/LibWeb/CSS/MediaQuery.h b/Userland/Libraries/LibWeb/CSS/MediaQuery.h
index 5cb14662bf6..845918cedf4 100644
--- a/Userland/Libraries/LibWeb/CSS/MediaQuery.h
+++ b/Userland/Libraries/LibWeb/CSS/MediaQuery.h
@@ -101,25 +101,25 @@ namespace AK {
 
 template<>
 struct Formatter<Web::CSS::MediaQuery::MediaFeature> : Formatter<StringView> {
-    void format(FormatBuilder& builder, Web::CSS::MediaQuery::MediaFeature const& media_feature)
+    ErrorOr<void> format(FormatBuilder& builder, Web::CSS::MediaQuery::MediaFeature const& media_feature)
     {
-        Formatter<StringView>::format(builder, media_feature.to_string());
+        return Formatter<StringView>::format(builder, media_feature.to_string());
     }
 };
 
 template<>
 struct Formatter<Web::CSS::MediaQuery::MediaCondition> : Formatter<StringView> {
-    void format(FormatBuilder& builder, Web::CSS::MediaQuery::MediaCondition const& media_condition)
+    ErrorOr<void> format(FormatBuilder& builder, Web::CSS::MediaQuery::MediaCondition const& media_condition)
     {
-        Formatter<StringView>::format(builder, media_condition.to_string());
+        return Formatter<StringView>::format(builder, media_condition.to_string());
     }
 };
 
 template<>
 struct Formatter<Web::CSS::MediaQuery> : Formatter<StringView> {
-    void format(FormatBuilder& builder, Web::CSS::MediaQuery const& media_query)
+    ErrorOr<void> format(FormatBuilder& builder, Web::CSS::MediaQuery const& media_query)
     {
-        Formatter<StringView>::format(builder, media_query.to_string());
+        return Formatter<StringView>::format(builder, media_query.to_string());
     }
 };
 
diff --git a/Userland/Libraries/LibWeb/CSS/Selector.h b/Userland/Libraries/LibWeb/CSS/Selector.h
index fd7ba600232..2c613581031 100644
--- a/Userland/Libraries/LibWeb/CSS/Selector.h
+++ b/Userland/Libraries/LibWeb/CSS/Selector.h
@@ -151,9 +151,9 @@ namespace AK {
 
 template<>
 struct Formatter<Web::CSS::Selector> : Formatter<StringView> {
-    void format(FormatBuilder& builder, Web::CSS::Selector const& selector)
+    ErrorOr<void> format(FormatBuilder& builder, Web::CSS::Selector const& selector)
     {
-        Formatter<StringView>::format(builder, selector.serialize());
+        return Formatter<StringView>::format(builder, selector.serialize());
     }
 };
 
diff --git a/Userland/Libraries/LibWeb/DOM/Position.h b/Userland/Libraries/LibWeb/DOM/Position.h
index b6d1bd3ffbd..1fc5737af2f 100644
--- a/Userland/Libraries/LibWeb/DOM/Position.h
+++ b/Userland/Libraries/LibWeb/DOM/Position.h
@@ -51,9 +51,9 @@ private:
 namespace AK {
 template<>
 struct Formatter<Web::DOM::Position> : Formatter<StringView> {
-    void format(FormatBuilder& builder, const Web::DOM::Position& value)
+    ErrorOr<void> format(FormatBuilder& builder, Web::DOM::Position const& value)
     {
-        Formatter<StringView>::format(builder, value.to_string());
+        return Formatter<StringView>::format(builder, value.to_string());
     }
 };
 
diff --git a/Userland/Services/LookupServer/DNSAnswer.cpp b/Userland/Services/LookupServer/DNSAnswer.cpp
index b4c9e8fc9a5..54791175818 100644
--- a/Userland/Services/LookupServer/DNSAnswer.cpp
+++ b/Userland/Services/LookupServer/DNSAnswer.cpp
@@ -28,50 +28,42 @@ bool DNSAnswer::has_expired() const
 
 }
 
-void AK::Formatter<LookupServer::DNSRecordType>::format(AK::FormatBuilder& builder, LookupServer::DNSRecordType value)
+ErrorOr<void> AK::Formatter<LookupServer::DNSRecordType>::format(AK::FormatBuilder& builder, LookupServer::DNSRecordType value)
 {
     switch (value) {
     case LookupServer::DNSRecordType::A:
-        builder.put_string("A");
-        return;
+        return builder.put_string("A");
     case LookupServer::DNSRecordType::NS:
-        builder.put_string("NS");
-        return;
+        return builder.put_string("NS");
     case LookupServer::DNSRecordType::CNAME:
-        builder.put_string("CNAME");
-        return;
+        return builder.put_string("CNAME");
     case LookupServer::DNSRecordType::SOA:
-        builder.put_string("SOA");
-        return;
+        return builder.put_string("SOA");
     case LookupServer::DNSRecordType::PTR:
-        builder.put_string("PTR");
-        return;
+        return builder.put_string("PTR");
     case LookupServer::DNSRecordType::MX:
-        builder.put_string("MX");
-        return;
+        return builder.put_string("MX");
     case LookupServer::DNSRecordType::TXT:
-        builder.put_string("TXT");
-        return;
+        return builder.put_string("TXT");
     case LookupServer::DNSRecordType::AAAA:
-        builder.put_string("AAAA");
-        return;
+        return builder.put_string("AAAA");
     case LookupServer::DNSRecordType::SRV:
-        builder.put_string("SRV");
-        return;
+        return builder.put_string("SRV");
     }
 
-    builder.put_string("DNS record type ");
-    builder.put_u64((u16)value);
+    TRY(builder.put_string("DNS record type "));
+    TRY(builder.put_u64((u16)value));
+    return {};
 }
 
-void AK::Formatter<LookupServer::DNSRecordClass>::format(AK::FormatBuilder& builder, LookupServer::DNSRecordClass value)
+ErrorOr<void> AK::Formatter<LookupServer::DNSRecordClass>::format(AK::FormatBuilder& builder, LookupServer::DNSRecordClass value)
 {
     switch (value) {
     case LookupServer::DNSRecordClass::IN:
-        builder.put_string("IN");
-        return;
+        return builder.put_string("IN");
     }
 
-    builder.put_string("DNS record class ");
-    builder.put_u64((u16)value);
+    TRY(builder.put_string("DNS record class "));
+    TRY(builder.put_u64((u16)value));
+    return {};
 }
diff --git a/Userland/Services/LookupServer/DNSAnswer.h b/Userland/Services/LookupServer/DNSAnswer.h
index 8b8560efdd0..4cf3db4df6f 100644
--- a/Userland/Services/LookupServer/DNSAnswer.h
+++ b/Userland/Services/LookupServer/DNSAnswer.h
@@ -65,7 +65,7 @@ struct AK::Formatter<LookupServer::DNSRecordType> : StandardFormatter {
     {
     }
 
-    void format(AK::FormatBuilder&, LookupServer::DNSRecordType);
+    ErrorOr<void> format(AK::FormatBuilder&, LookupServer::DNSRecordType);
 };
 
 template<>
@@ -76,5 +76,5 @@ struct AK::Formatter<LookupServer::DNSRecordClass> : StandardFormatter {
     {
     }
 
-    void format(AK::FormatBuilder&, LookupServer::DNSRecordClass);
+    ErrorOr<void> format(AK::FormatBuilder&, LookupServer::DNSRecordClass);
 };
diff --git a/Userland/Services/LookupServer/DNSName.h b/Userland/Services/LookupServer/DNSName.h
index 17fbe7a5577..3a2cb4ba1da 100644
--- a/Userland/Services/LookupServer/DNSName.h
+++ b/Userland/Services/LookupServer/DNSName.h
@@ -41,7 +41,7 @@ OutputStream& operator<<(OutputStream& stream, const DNSName&);
 
 template<>
 struct AK::Formatter<LookupServer::DNSName> : Formatter<StringView> {
-    void format(FormatBuilder& builder, const LookupServer::DNSName& value)
+    ErrorOr<void> format(FormatBuilder& builder, LookupServer::DNSName const& value)
     {
         return Formatter<StringView>::format(builder, value.as_string());
     }
diff --git a/Userland/Shell/AST.cpp b/Userland/Shell/AST.cpp
index a32c22f69ee..09587b3573f 100644
--- a/Userland/Shell/AST.cpp
+++ b/Userland/Shell/AST.cpp
@@ -19,7 +19,7 @@
 #include <signal.h>
 #include <unistd.h>
 
-void AK::Formatter<Shell::AST::Command>::format(FormatBuilder& builder, const Shell::AST::Command& value)
+ErrorOr<void> AK::Formatter<Shell::AST::Command>::format(FormatBuilder& builder, Shell::AST::Command const& value)
 {
     if (m_sign_mode != FormatBuilder::SignMode::Default)
         VERIFY_NOT_REACHED();
@@ -35,46 +35,46 @@ void AK::Formatter<Shell::AST::Command>::format(FormatBuilder& builder, const Sh
         VERIFY_NOT_REACHED();
 
     if (value.argv.is_empty()) {
-        builder.put_literal("(ShellInternal)");
+        TRY(builder.put_literal("(ShellInternal)"));
     } else {
         bool first = true;
         for (auto& arg : value.argv) {
             if (!first)
-                builder.put_literal(" ");
+                TRY(builder.put_literal(" "));
             first = false;
-            builder.put_literal(arg);
+            TRY(builder.put_literal(arg));
         }
     }
 
     for (auto& redir : value.redirections) {
-        builder.put_padding(' ', 1);
+        TRY(builder.put_padding(' ', 1));
         if (redir.is_path_redirection()) {
             auto path_redir = (const Shell::AST::PathRedirection*)&redir;
-            builder.put_i64(path_redir->fd);
+            TRY(builder.put_i64(path_redir->fd));
             switch (path_redir->direction) {
             case Shell::AST::PathRedirection::Read:
-                builder.put_literal("<");
+                TRY(builder.put_literal("<"));
                 break;
             case Shell::AST::PathRedirection::Write:
-                builder.put_literal(">");
+                TRY(builder.put_literal(">"));
                 break;
             case Shell::AST::PathRedirection::WriteAppend:
-                builder.put_literal(">>");
+                TRY(builder.put_literal(">>"));
                 break;
             case Shell::AST::PathRedirection::ReadWrite:
-                builder.put_literal("<>");
+                TRY(builder.put_literal("<>"));
                 break;
             }
-            builder.put_literal(path_redir->path);
+            TRY(builder.put_literal(path_redir->path));
         } else if (redir.is_fd_redirection()) {
             auto* fdredir = (const Shell::AST::FdRedirection*)&redir;
-            builder.put_i64(fdredir->new_fd);
-            builder.put_literal(">");
-            builder.put_i64(fdredir->old_fd);
+            TRY(builder.put_i64(fdredir->new_fd));
+            TRY(builder.put_literal(">"));
+            TRY(builder.put_i64(fdredir->old_fd));
         } else if (redir.is_close_redirection()) {
             auto close_redir = (const Shell::AST::CloseRedirection*)&redir;
-            builder.put_i64(close_redir->fd);
-            builder.put_literal(">&-");
+            TRY(builder.put_i64(close_redir->fd));
+            TRY(builder.put_literal(">&-"));
         } else {
             VERIFY_NOT_REACHED();
         }
@@ -84,23 +84,24 @@ void AK::Formatter<Shell::AST::Command>::format(FormatBuilder& builder, const Sh
         for (auto& command : value.next_chain) {
             switch (command.action) {
             case Shell::AST::NodeWithAction::And:
-                builder.put_literal(" && ");
+                TRY(builder.put_literal(" && "));
                 break;
             case Shell::AST::NodeWithAction::Or:
-                builder.put_literal(" || ");
+                TRY(builder.put_literal(" || "));
                 break;
             case Shell::AST::NodeWithAction::Sequence:
-                builder.put_literal("; ");
+                TRY(builder.put_literal("; "));
                 break;
             }
 
-            builder.put_literal("(");
-            builder.put_literal(command.node->class_name());
-            builder.put_literal("...)");
+            TRY(builder.put_literal("("));
+            TRY(builder.put_literal(command.node->class_name()));
+            TRY(builder.put_literal("...)"));
         }
     }
     if (!value.should_wait)
-        builder.put_literal("&");
+        TRY(builder.put_literal("&"));
+    return {};
 }
 
 namespace Shell::AST {
diff --git a/Userland/Shell/AST.h b/Userland/Shell/AST.h
index 4f3722854fd..7661b68b565 100644
--- a/Userland/Shell/AST.h
+++ b/Userland/Shell/AST.h
@@ -1512,7 +1512,7 @@ struct Formatter<Shell::AST::Command> : StandardFormatter {
     {
     }
 
-    void format(FormatBuilder&, const Shell::AST::Command& value);
+    ErrorOr<void> format(FormatBuilder&, Shell::AST::Command const& value);
 };
 
 }
diff --git a/Userland/Utilities/strace.cpp b/Userland/Utilities/strace.cpp
index b4669fd8565..8b300af9372 100644
--- a/Userland/Utilities/strace.cpp
+++ b/Userland/Utilities/strace.cpp
@@ -273,7 +273,7 @@ struct Formatter<BitflagDerivative> : StandardFormatter {
     {
     }
 
-    void format(FormatBuilder& format_builder, BitflagDerivative const& value)
+    ErrorOr<void> format(FormatBuilder& format_builder, BitflagDerivative const& value)
     {
         bool had_any_output = false;
         int remaining = value.flagset;
@@ -283,25 +283,27 @@ struct Formatter<BitflagDerivative> : StandardFormatter {
                 continue;
             remaining &= ~option.value;
             if (had_any_output)
-                format_builder.put_literal(" | ");
-            format_builder.put_literal(option.name);
+                TRY(format_builder.put_literal(" | "));
+            TRY(format_builder.put_literal(option.name));
             had_any_output = true;
         }
 
         if (remaining != 0) {
             // No more BitflagOptions are available. Any remaining flags are unrecognized.
             if (had_any_output)
-                format_builder.put_literal(" | ");
+                TRY(format_builder.put_literal(" | "));
             format_builder.builder().appendff("0x{:x} (?)", static_cast<unsigned>(remaining));
             had_any_output = true;
         }
 
         if (!had_any_output) {
             if constexpr (requires { BitflagDerivative::default_; })
-                format_builder.put_literal(BitflagDerivative::default_);
+                TRY(format_builder.put_literal(BitflagDerivative::default_));
             else
-                format_builder.put_literal("0");
+                TRY(format_builder.put_literal("0"));
         }
+
+        return {};
     }
 };
 }
@@ -319,13 +321,14 @@ struct Formatter<PointerArgument> : StandardFormatter {
     {
     }
 
-    void format(FormatBuilder& format_builder, PointerArgument const& value)
+    ErrorOr<void> format(FormatBuilder& format_builder, PointerArgument const& value)
     {
         auto& builder = format_builder.builder();
         if (value.value == nullptr)
             builder.append("null");
         else
             builder.appendff("{}", value.value);
+        return {};
     }
 };
 }
@@ -478,25 +481,27 @@ static void format_ioctl(FormattedSyscallBuilder& builder, int fd, unsigned requ
 namespace AK {
 template<>
 struct Formatter<struct timespec> : StandardFormatter {
-    void format(FormatBuilder& format_builder, struct timespec value)
+    ErrorOr<void> format(FormatBuilder& format_builder, struct timespec value)
     {
         auto& builder = format_builder.builder();
         builder.appendff("{{tv_sec={}, tv_nsec={}}}", value.tv_sec, value.tv_nsec);
+        return {};
     }
 };
 
 template<>
 struct Formatter<struct timeval> : StandardFormatter {
-    void format(FormatBuilder& format_builder, struct timeval value)
+    ErrorOr<void> format(FormatBuilder& format_builder, struct timeval value)
     {
         auto& builder = format_builder.builder();
         builder.appendff("{{tv_sec={}, tv_usec={}}}", value.tv_sec, value.tv_usec);
+        return {};
     }
 };
 
 template<>
 struct Formatter<struct stat> : StandardFormatter {
-    void format(FormatBuilder& format_builder, struct stat value)
+    ErrorOr<void> format(FormatBuilder& format_builder, struct stat value)
     {
         auto& builder = format_builder.builder();
         builder.appendff(
@@ -504,6 +509,7 @@ struct Formatter<struct stat> : StandardFormatter {
             "st_size={}, st_blksize={}, st_blocks={}, st_atim={}, st_mtim={}, st_ctim={}}}",
             value.st_dev, value.st_ino, value.st_mode, value.st_nlink, value.st_uid, value.st_gid, value.st_rdev,
             value.st_size, value.st_blksize, value.st_blocks, value.st_atim, value.st_mtim, value.st_ctim);
+        return {};
     }
 };
 }
@@ -561,7 +567,7 @@ static void format_select(FormattedSyscallBuilder& builder, Syscall::SC_select_p
 namespace AK {
 template<>
 struct Formatter<struct sockaddr> : StandardFormatter {
-    void format(FormatBuilder& format_builder, struct sockaddr address)
+    ErrorOr<void> format(FormatBuilder& format_builder, struct sockaddr address)
     {
         auto& builder = format_builder.builder();
         builder.append("{sa_family=");
@@ -579,6 +585,7 @@ struct Formatter<struct sockaddr> : StandardFormatter {
                 address_un->sun_path);
         }
         builder.append('}');
+        return {};
     }
 };
 }
diff --git a/Userland/Utilities/syscall.cpp b/Userland/Utilities/syscall.cpp
index de119af74a0..4eaf603f7db 100644
--- a/Userland/Utilities/syscall.cpp
+++ b/Userland/Utilities/syscall.cpp
@@ -28,7 +28,7 @@ static FlatPtr parse_from(ArgIter&);
 
 template<>
 struct AK::Formatter<Syscall::Function> : Formatter<StringView> {
-    void format(FormatBuilder& builder, Syscall::Function function)
+    ErrorOr<void> format(FormatBuilder& builder, Syscall::Function function)
     {
         return Formatter<StringView>::format(builder, to_string(function));
     }