diff --git a/CHANGELOG.md b/CHANGELOG.md
index d796970..520c05a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+In Development
+--------------
+
+* Fixed S3 backups which broke with duplicity 0.8.23.
+
 Version 56 (January 19, 2022)
 -----------------------------
 
diff --git a/management/backup.py b/management/backup.py
index bc3ac5b..26a61a0 100755
--- a/management/backup.py
+++ b/management/backup.py
@@ -59,7 +59,7 @@ def backup_status(env):
 		"--archive-dir", backup_cache_dir,
 		"--gpg-options", "--cipher-algo=AES256",
 		"--log-fd", "1",
-		config["target"],
+		get_duplicity_target_url(config),
 		] + get_duplicity_additional_args(env),
 		get_duplicity_env_vars(env),
 		trap=True)
@@ -190,13 +190,45 @@ def get_passphrase(env):
 
 	return passphrase
 
+def get_duplicity_target_url(config):
+	target = config["target"]
+
+	if get_target_type(config) == "s3":
+		from urllib.parse import urlsplit, urlunsplit
+		target = list(urlsplit(target))
+
+		# Duplicity now defaults to boto3 as the backend for S3, but we have
+		# legacy boto installed (boto3 doesn't support Ubuntu 18.04) so
+		# we retarget for classic boto.
+		target[0] = "boto+" + target[0]
+
+		# In addition, although we store the S3 hostname in the target URL,
+		# duplicity no longer accepts it in the target URL. The hostname in
+		# the target URL must be the bucket name. The hostname is passed
+		# via get_duplicity_additional_args. Move the first part of the
+		# path (the bucket name) into the hostname URL component, and leave
+		# the rest for the path.
+		target[1], target[2] = target[2].lstrip('/').split('/', 1)
+
+		target = urlunsplit(target)
+
+	return target
+
 def get_duplicity_additional_args(env):
 	config = get_backup_config(env)
+
 	if get_target_type(config) == 'rsync':
 		return [
 			"--ssh-options= -i /root/.ssh/id_rsa_miab",
 			"--rsync-options= -e \"/usr/bin/ssh -oStrictHostKeyChecking=no -oBatchMode=yes -p 22 -i /root/.ssh/id_rsa_miab\"",
 		]
+	elif get_target_type(config) == 's3':
+		# See note about hostname in get_duplicity_target_url.
+		from urllib.parse import urlsplit, urlunsplit
+		target = urlsplit(config["target"])
+		endpoint_url = urlunsplit(("https", target.netloc, '', '', ''))
+		return ["--s3-endpoint-url",  endpoint_url]
+
 	return []
 
 def get_duplicity_env_vars(env):
@@ -277,7 +309,7 @@ def perform_backup(full_backup):
 			"--volsize", "250",
 			"--gpg-options", "--cipher-algo=AES256",
 			env["STORAGE_ROOT"],
-			config["target"],
+			get_duplicity_target_url(config),
 			"--allow-source-mismatch"
 			] + get_duplicity_additional_args(env),
 			get_duplicity_env_vars(env))
@@ -296,7 +328,7 @@ def perform_backup(full_backup):
 		"--verbosity", "error",
 		"--archive-dir", backup_cache_dir,
 		"--force",
-		config["target"]
+		get_duplicity_target_url(config)
 		] + get_duplicity_additional_args(env),
 		get_duplicity_env_vars(env))
 
@@ -311,7 +343,7 @@ def perform_backup(full_backup):
 		"--verbosity", "error",
 		"--archive-dir", backup_cache_dir,
 		"--force",
-		config["target"]
+		get_duplicity_target_url(config)
 		] + get_duplicity_additional_args(env),
 		get_duplicity_env_vars(env))
 
@@ -349,7 +381,7 @@ def run_duplicity_verification():
 		"--compare-data",
 		"--archive-dir", backup_cache_dir,
 		"--exclude", backup_root,
-		config["target"],
+		get_duplicity_target_url(config),
 		env["STORAGE_ROOT"],
 	] + get_duplicity_additional_args(env), get_duplicity_env_vars(env))
 
@@ -361,7 +393,7 @@ def run_duplicity_restore(args):
 		"/usr/bin/duplicity",
 		"restore",
 		"--archive-dir", backup_cache_dir,
-		config["target"],
+		get_duplicity_target_url(config),
 		] + get_duplicity_additional_args(env) + args,
 	get_duplicity_env_vars(env))
 
diff --git a/management/status_checks.py b/management/status_checks.py
index c66bf9b..220e23e 100755
--- a/management/status_checks.py
+++ b/management/status_checks.py
@@ -253,6 +253,18 @@ def check_free_disk_space(rounded_values, env, output):
 		if rounded_values: disk_msg = "The disk has less than 15% free space."
 		output.print_error(disk_msg)
 
+	# Check that there's only one duplicity cache. If there's more than one,
+	# it's probably no longer in use, and we can recommend clearing the cache
+	# to save space. The cache directory may not exist yet, which is OK.
+	backup_cache_path = os.path.join(env['STORAGE_ROOT'], 'backup/cache')
+	try:
+		backup_cache_count = len(os.listdir(backup_cache_path))
+	except:
+		backup_cache_count = 0
+	if backup_cache_count > 1:
+		output.print_warning("The backup cache directory {} has more than one backup target cache. Consider clearing this directory to save disk space."
+			.format(backup_cache_path))
+
 def check_free_memory(rounded_values, env, output):
 	# Check free memory.
 	percent_free = 100 - psutil.virtual_memory().percent