diff --git a/src/main/java/org/codelibs/fess/es/config/exentity/DataConfig.java b/src/main/java/org/codelibs/fess/es/config/exentity/DataConfig.java
index 7363b1338..4eb6ff55e 100644
--- a/src/main/java/org/codelibs/fess/es/config/exentity/DataConfig.java
+++ b/src/main/java/org/codelibs/fess/es/config/exentity/DataConfig.java
@@ -87,7 +87,7 @@ public class DataConfig extends BsDataConfig implements CrawlingConfig {
 
     @Override
     public String getDocumentBoost() {
-        return Float.valueOf(getBoost().floatValue()).toString();
+        return getBoost().toString();
     }
 
     public String getBoostValue() {
diff --git a/src/main/java/org/codelibs/fess/es/config/exentity/FileConfig.java b/src/main/java/org/codelibs/fess/es/config/exentity/FileConfig.java
index de9657850..e48aa0430 100644
--- a/src/main/java/org/codelibs/fess/es/config/exentity/FileConfig.java
+++ b/src/main/java/org/codelibs/fess/es/config/exentity/FileConfig.java
@@ -56,7 +56,7 @@ public class FileConfig extends BsFileConfig implements CrawlingConfig {
 
     @Override
     public String getDocumentBoost() {
-        return Float.valueOf(getBoost().floatValue()).toString();
+        return getBoost().toString();
     }
 
     @Override
diff --git a/src/main/java/org/codelibs/fess/es/config/exentity/WebConfig.java b/src/main/java/org/codelibs/fess/es/config/exentity/WebConfig.java
index 7fc921df1..2225ccd99 100644
--- a/src/main/java/org/codelibs/fess/es/config/exentity/WebConfig.java
+++ b/src/main/java/org/codelibs/fess/es/config/exentity/WebConfig.java
@@ -57,7 +57,7 @@ public class WebConfig extends BsWebConfig implements CrawlingConfig {
 
     @Override
     public String getDocumentBoost() {
-        return Float.valueOf(getBoost().floatValue()).toString();
+        return getBoost().toString();
     }
 
     @Override
diff --git a/src/main/java/org/codelibs/fess/exception/UserRoleLoginException.java b/src/main/java/org/codelibs/fess/exception/UserRoleLoginException.java
index 7b5b15fef..3ec26da39 100644
--- a/src/main/java/org/codelibs/fess/exception/UserRoleLoginException.java
+++ b/src/main/java/org/codelibs/fess/exception/UserRoleLoginException.java
@@ -32,7 +32,7 @@ public class UserRoleLoginException extends RuntimeException {
     }
 
     @Override
-    public Throwable fillInStackTrace() {
+    public synchronized Throwable fillInStackTrace() {
         return null;
     }
 }
diff --git a/src/main/java/org/codelibs/fess/ldap/LdapManager.java b/src/main/java/org/codelibs/fess/ldap/LdapManager.java
index 58e7cf836..21cc26c70 100644
--- a/src/main/java/org/codelibs/fess/ldap/LdapManager.java
+++ b/src/main/java/org/codelibs/fess/ldap/LdapManager.java
@@ -459,7 +459,7 @@ public class LdapManager {
                                 name -> {
                                     search(fessConfig.getLdapAdminGroupBaseDn(), fessConfig.getLdapAdminGroupFilter(name), null, adminEnv,
                                             subResult -> {
-                                                if (!!subResult.isEmpty()) {
+                                                if (subResult.isEmpty()) {
                                                     final Group group = new Group();
                                                     group.setName(name);
                                                     insert(group);
@@ -492,7 +492,7 @@ public class LdapManager {
                                 name -> {
                                     search(fessConfig.getLdapAdminRoleBaseDn(), fessConfig.getLdapAdminRoleFilter(name), null, adminEnv,
                                             subResult -> {
-                                                if (!!subResult.isEmpty()) {
+                                                if (subResult.isEmpty()) {
                                                     final Role role = new Role();
                                                     role.setName(name);
                                                     insert(role);
@@ -507,7 +507,7 @@ public class LdapManager {
                                 stream -> stream.forEach(name -> {
                                     search(fessConfig.getLdapAdminGroupBaseDn(), fessConfig.getLdapAdminGroupFilter(name), null, adminEnv,
                                             subResult -> {
-                                                if (!!subResult.isEmpty()) {
+                                                if (subResult.isEmpty()) {
                                                     final Group group = new Group();
                                                     group.setName(name);
                                                     insert(group);
@@ -522,7 +522,7 @@ public class LdapManager {
                                 stream -> stream.forEach(name -> {
                                     search(fessConfig.getLdapAdminRoleBaseDn(), fessConfig.getLdapAdminRoleFilter(name), null, adminEnv,
                                             subResult -> {
-                                                if (!!subResult.isEmpty()) {
+                                                if (subResult.isEmpty()) {
                                                     final Role role = new Role();
                                                     role.setName(name);
                                                     insert(role);
@@ -869,7 +869,7 @@ public class LdapManager {
 
         stream(user.getGroupNames()).of(stream -> stream.forEach(name -> {
             search(fessConfig.getLdapAdminGroupBaseDn(), fessConfig.getLdapAdminGroupFilter(name), null, adminEnv, subResult -> {
-                if (!!subResult.isEmpty()) {
+                if (subResult.isEmpty()) {
                     final Group group = new Group();
                     group.setName(name);
                     insert(group);
@@ -881,7 +881,7 @@ public class LdapManager {
         }));
         stream(user.getRoleNames()).of(stream -> stream.forEach(name -> {
             search(fessConfig.getLdapAdminRoleBaseDn(), fessConfig.getLdapAdminRoleFilter(name), null, adminEnv, subResult -> {
-                if (!!subResult.isEmpty()) {
+                if (subResult.isEmpty()) {
                     final Role role = new Role();
                     role.setName(name);
                     insert(role);