diff --git a/CHANGELOG.md b/CHANGELOG.md
index fab3104bac40fd..b9834dcaef1206 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,40 @@
 
 All notable changes to this project will be documented in this file.
 
+## [4.2.1] - UNRELEASED
+
+### Added
+
+- Add redirection on `/deck` URLs for logged-out users ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27128))
+- Add support for v4.2.0 migrations to `tootctl maintenance fix-duplicates` ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27147))
+
+### Changed
+
+- Change some worker lock TTLs to be shorter-lived ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27246))
+- Change user archive export allowed period from 7 days to 6 days ([suddjian](https://github.com/mastodon/mastodon/pull/27200))
+
+### Fixed
+
+- Fix unexpected linebreak in version string in the Web UI ([vmstan](https://github.com/mastodon/mastodon/pull/26986))
+- Fix double scroll bars in some columns in advanced interface ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27187))
+- Fix boosts of local users being filtered in account timelines ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27204))
+- Fix multiple instances of the trend refresh scheduler sometimes running at once ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27253))
+- Fix importer returning negative row estimates ([jgillich](https://github.com/mastodon/mastodon/pull/27258))
+- Fix incorrectly keeping outdated update notices absent from the API endpoint ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27021))
+- Fix import progress not updating on certain failures ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27247))
+- Fix websocket connections being incorrectly decremented twice on errors ([ThisIsMissEm](https://github.com/mastodon/mastodon/pull/27238))
+- Fix explore prompt appearing because of posts being received out of order ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27211))
+- Fix explore prompt sometimes showing up when the home TL is loading ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27062))
+- Fix link handling of mentions in user profiles when logged out ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27185))
+- Fix filtering audit log for entries about disabling 2FA ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27186))
+- Fix notification toasts not respecting reduce-motion ([c960657](https://github.com/mastodon/mastodon/pull/27178))
+- Fix retention dashboard not displaying correct month ([vmstan](https://github.com/mastodon/mastodon/pull/27180))
+- Fix tIME chunk not being properly removed from PNG uploads ([TheEssem](https://github.com/mastodon/mastodon/pull/27111))
+- Fix division by zero in video in bitrate computation code ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27129))
+- Fix inefficient queries in “Follows and followers” as well as several admin pages ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27116))
+- Fix ActiveRecord using two connection pools when no replica is defined ([ClearlyClaire](https://github.com/mastodon/mastodon/pull/27061))
+- Fix the search documentation URL in system checks ([renchap](https://github.com/mastodon/mastodon/pull/27036))
+
 ## [4.2.0] - 2023-09-21
 
 The following changelog entries focus on changes visible to users, administrators, client developers or federated software developers, but there has also been a lot of code modernization, refactoring, and tooling work, in particular by [@danielmbrasil](https://github.com/danielmbrasil), [@mjankowski](https://github.com/mjankowski), [@nschonni](https://github.com/nschonni), [@renchap](https://github.com/renchap), and [@takayamaki](https://github.com/takayamaki).
diff --git a/docker-compose.yml b/docker-compose.yml
index d19f278f75fe0f..1a180b089070f1 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -56,7 +56,7 @@ services:
 
   web:
     build: .
-    image: ghcr.io/mastodon/mastodon:v4.2.0
+    image: ghcr.io/mastodon/mastodon:v4.2.1
     restart: always
     env_file: .env.production
     command: bash -c "rm -f /mastodon/tmp/pids/server.pid; bundle exec rails s -p 3000"
@@ -77,7 +77,7 @@ services:
 
   streaming:
     build: .
-    image: ghcr.io/mastodon/mastodon:v4.2.0
+    image: ghcr.io/mastodon/mastodon:v4.2.1
     restart: always
     env_file: .env.production
     command: node ./streaming
@@ -95,7 +95,7 @@ services:
 
   sidekiq:
     build: .
-    image: ghcr.io/mastodon/mastodon:v4.2.0
+    image: ghcr.io/mastodon/mastodon:v4.2.1
     restart: always
     env_file: .env.production
     command: bundle exec sidekiq
diff --git a/lib/mastodon/version.rb b/lib/mastodon/version.rb
index 46c07596d1492b..5e07f508bbf696 100644
--- a/lib/mastodon/version.rb
+++ b/lib/mastodon/version.rb
@@ -13,11 +13,11 @@ def minor
     end
 
     def patch
-      0
+      1
     end
 
     def default_prerelease
-      ''
+      'rc1'
     end
 
     def prerelease