diff --git a/CHANGES.md b/CHANGES.md
index 535c41f6a6..20177bf00a 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,50 @@
+# Synapse 1.121.0rc1 (2024-12-04)
+
+This release candidate contains the security fixes from [v1.120.2](https://github.com/element-hq/synapse/releases/tag/v1.120.2).
+
+New changes listed below.
+
+### Features
+
+- Support for [MSC4190](https://github.com/matrix-org/matrix-spec-proposals/pull/4190): device management for Application Services. ([\#17705](https://github.com/element-hq/synapse/issues/17705))
+- Update [MSC4186](https://github.com/matrix-org/matrix-spec-proposals/pull/4186) Sliding Sync to include invite, ban, kick, targets when `$LAZY`-loading room members. ([\#17947](https://github.com/element-hq/synapse/issues/17947))
+- Use stable `M_USER_LOCKED` error code for locked accounts, as per [Matrix 1.12](https://spec.matrix.org/v1.12/client-server-api/#account-locking). ([\#17965](https://github.com/element-hq/synapse/issues/17965))
+- [MSC4076](https://github.com/matrix-org/matrix-spec-proposals/pull/4076): Add `disable_badge_count` to pusher configuration. ([\#17975](https://github.com/element-hq/synapse/issues/17975))
+
+### Bugfixes
+
+- Fix long-standing bug where read receipts could get overly delayed being sent over federation. ([\#17933](https://github.com/element-hq/synapse/issues/17933))
+
+### Improved Documentation
+
+- Add OIDC example configuration for Forgejo (fork of Gitea). ([\#17872](https://github.com/element-hq/synapse/issues/17872))
+- Link to element-docker-demo from contrib/docker*. ([\#17953](https://github.com/element-hq/synapse/issues/17953))
+
+### Internal Changes
+
+- [MSC4108](https://github.com/matrix-org/matrix-spec-proposals/pull/4108): Add a `Content-Type` header on the `PUT` response to work around a faulty behavior in some caching reverse proxies. ([\#17253](https://github.com/element-hq/synapse/issues/17253))
+- Fix incorrect comment in new schema delta. ([\#17936](https://github.com/element-hq/synapse/issues/17936))
+- Raise setuptools_rust version cap to 1.10.2. ([\#17944](https://github.com/element-hq/synapse/issues/17944))
+- Enable encrypted appservice related experimental features in the complement docker image. ([\#17945](https://github.com/element-hq/synapse/issues/17945))
+- Return whether the user is suspended when querying the user account in the Admin API. ([\#17952](https://github.com/element-hq/synapse/issues/17952))
+- Fix new scheduled tasks jumping the queue. ([\#17962](https://github.com/element-hq/synapse/issues/17962))
+- Bump pyo3 and dependencies to v0.23.2. ([\#17966](https://github.com/element-hq/synapse/issues/17966))
+- Update setuptools-rust and fix building abi3 wheels in latest version. ([\#17969](https://github.com/element-hq/synapse/issues/17969))
+- Consolidate SSO redirects through `/_matrix/client/v3/login/sso/redirect(/{idpId})`. ([\#17972](https://github.com/element-hq/synapse/issues/17972))
+- Fix Docker and Complement config to be able to use `public_baseurl`. ([\#17986](https://github.com/element-hq/synapse/issues/17986))
+- Fix building wheels for MacOS which was temporarily disabled in Synapse 1.120.2. ([\#17993](https://github.com/element-hq/synapse/issues/17993))
+- Fix release process to not create duplicate releases. ([\#17970](https://github.com/element-hq/synapse/issues/17970), [\#17995](https://github.com/element-hq/synapse/issues/17995))
+
+
+### Updates to locked dependencies
+
+* Bump bytes from 1.8.0 to 1.9.0. ([\#17982](https://github.com/element-hq/synapse/issues/17982))
+* Bump pysaml2 from 7.3.1 to 7.5.0. ([\#17978](https://github.com/element-hq/synapse/issues/17978))
+* Bump serde_json from 1.0.132 to 1.0.133. ([\#17939](https://github.com/element-hq/synapse/issues/17939))
+* Bump tomli from 2.0.2 to 2.1.0. ([\#17959](https://github.com/element-hq/synapse/issues/17959))
+* Bump tomli from 2.1.0 to 2.2.1. ([\#17979](https://github.com/element-hq/synapse/issues/17979))
+* Bump tornado from 6.4.1 to 6.4.2. ([\#17955](https://github.com/element-hq/synapse/issues/17955))
+
 # Synapse 1.120.2 (2024-12-03)
 
 This version has building of wheels for macOS disabled.
diff --git a/changelog.d/17253.misc b/changelog.d/17253.misc
deleted file mode 100644
index 868691624d..0000000000
--- a/changelog.d/17253.misc
+++ /dev/null
@@ -1 +0,0 @@
-[MSC4108](https://github.com/matrix-org/matrix-spec-proposals/pull/4108): Add a `Content-Type` header on the `PUT` response to work around a faulty behavior in some caching reverse proxies.
diff --git a/changelog.d/17705.feature b/changelog.d/17705.feature
deleted file mode 100644
index e2cd7bca4f..0000000000
--- a/changelog.d/17705.feature
+++ /dev/null
@@ -1 +0,0 @@
-Support for [MSC4190](https://github.com/matrix-org/matrix-spec-proposals/pull/4190): device management for Application Services.
diff --git a/changelog.d/17872.doc b/changelog.d/17872.doc
deleted file mode 100644
index 7f8b2d3495..0000000000
--- a/changelog.d/17872.doc
+++ /dev/null
@@ -1 +0,0 @@
-Add OIDC example configuration for Forgejo (fork of Gitea).
diff --git a/changelog.d/17933.bugfix b/changelog.d/17933.bugfix
deleted file mode 100644
index 8d30ac587e..0000000000
--- a/changelog.d/17933.bugfix
+++ /dev/null
@@ -1 +0,0 @@
-Fix long-standing bug where read receipts could get overly delayed being sent over federation.
diff --git a/changelog.d/17936.misc b/changelog.d/17936.misc
deleted file mode 100644
index 91d976fbd9..0000000000
--- a/changelog.d/17936.misc
+++ /dev/null
@@ -1 +0,0 @@
-Fix incorrect comment in new schema delta.
diff --git a/changelog.d/17944.misc b/changelog.d/17944.misc
deleted file mode 100644
index a8a645103f..0000000000
--- a/changelog.d/17944.misc
+++ /dev/null
@@ -1 +0,0 @@
-Raise setuptools_rust version cap to 1.10.2.
\ No newline at end of file
diff --git a/changelog.d/17945.misc b/changelog.d/17945.misc
deleted file mode 100644
index eeebb92169..0000000000
--- a/changelog.d/17945.misc
+++ /dev/null
@@ -1 +0,0 @@
-Enable encrypted appservice related experimental features in the complement docker image.
diff --git a/changelog.d/17947.feature b/changelog.d/17947.feature
deleted file mode 100644
index 2d1b99cec2..0000000000
--- a/changelog.d/17947.feature
+++ /dev/null
@@ -1 +0,0 @@
-Update [MSC4186](https://github.com/matrix-org/matrix-spec-proposals/pull/4186) Sliding Sync to include invite, ban, kick, targets when `$LAZY`-loading room members.
diff --git a/changelog.d/17952.misc b/changelog.d/17952.misc
deleted file mode 100644
index 84fc8bfc29..0000000000
--- a/changelog.d/17952.misc
+++ /dev/null
@@ -1 +0,0 @@
-Return whether the user is suspended when querying the user account in the Admin API.
\ No newline at end of file
diff --git a/changelog.d/17953.doc b/changelog.d/17953.doc
deleted file mode 100644
index 10f5a27ba9..0000000000
--- a/changelog.d/17953.doc
+++ /dev/null
@@ -1 +0,0 @@
-Link to element-docker-demo from contrib/docker*.
diff --git a/changelog.d/17962.misc b/changelog.d/17962.misc
deleted file mode 100644
index adf6348707..0000000000
--- a/changelog.d/17962.misc
+++ /dev/null
@@ -1 +0,0 @@
-Fix new scheduled tasks jumping the queue.
diff --git a/changelog.d/17965.feature b/changelog.d/17965.feature
deleted file mode 100644
index e447a58986..0000000000
--- a/changelog.d/17965.feature
+++ /dev/null
@@ -1 +0,0 @@
-Use stable `M_USER_LOCKED` error code for locked accounts, as per [Matrix 1.12](https://spec.matrix.org/v1.12/client-server-api/#account-locking).
\ No newline at end of file
diff --git a/changelog.d/17966.misc b/changelog.d/17966.misc
deleted file mode 100644
index c6d6e55fbf..0000000000
--- a/changelog.d/17966.misc
+++ /dev/null
@@ -1 +0,0 @@
-Bump pyo3 and dependencies to v0.23.2.
\ No newline at end of file
diff --git a/changelog.d/17969.misc b/changelog.d/17969.misc
deleted file mode 100644
index 05506daaa0..0000000000
--- a/changelog.d/17969.misc
+++ /dev/null
@@ -1 +0,0 @@
-Update setuptools-rust and fix building abi3 wheels in latest version.
diff --git a/changelog.d/17970.bugfix b/changelog.d/17970.bugfix
deleted file mode 100644
index 835079de3f..0000000000
--- a/changelog.d/17970.bugfix
+++ /dev/null
@@ -1 +0,0 @@
-Fix release process to not create duplicate releases.
diff --git a/changelog.d/17972.misc b/changelog.d/17972.misc
deleted file mode 100644
index e7f009d20d..0000000000
--- a/changelog.d/17972.misc
+++ /dev/null
@@ -1 +0,0 @@
-Consolidate SSO redirects through `/_matrix/client/v3/login/sso/redirect(/{idpId})`.
diff --git a/changelog.d/17975.feature b/changelog.d/17975.feature
deleted file mode 100644
index 48f41bddad..0000000000
--- a/changelog.d/17975.feature
+++ /dev/null
@@ -1 +0,0 @@
-[MSC4076](https://github.com/matrix-org/matrix-spec-proposals/pull/4076): Add `disable_badge_count` to pusher configuration.
diff --git a/changelog.d/17986.misc b/changelog.d/17986.misc
deleted file mode 100644
index c062f3ecdf..0000000000
--- a/changelog.d/17986.misc
+++ /dev/null
@@ -1 +0,0 @@
-Fix Docker and Complement config to be able to use `public_baseurl`.
diff --git a/changelog.d/17993.misc b/changelog.d/17993.misc
deleted file mode 100644
index 149cb358c3..0000000000
--- a/changelog.d/17993.misc
+++ /dev/null
@@ -1 +0,0 @@
-Fix building wheels for MacOS which was temporarily disabled in Synapse 1.120.2.
\ No newline at end of file
diff --git a/changelog.d/17995.misc b/changelog.d/17995.misc
deleted file mode 100644
index d8e608c1ae..0000000000
--- a/changelog.d/17995.misc
+++ /dev/null
@@ -1 +0,0 @@
-Pin `softprops/action-gh-release` to v0.1.15 to work around https://github.com/softprops/action-gh-release/issues/445.
\ No newline at end of file
diff --git a/debian/changelog b/debian/changelog
index 3aa74d1d24..805c036c82 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+matrix-synapse-py3 (1.121.0~rc1) stable; urgency=medium
+
+  * New Synapse release 1.121.0rc1.
+
+ -- Synapse Packaging team <packages@matrix.org>  Wed, 04 Dec 2024 14:47:23 +0000
+
 matrix-synapse-py3 (1.120.2) stable; urgency=medium
 
   * New synapse release 1.120.2.
diff --git a/pyproject.toml b/pyproject.toml
index 60c62015b7..e5051770f5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -97,7 +97,7 @@ module-name = "synapse.synapse_rust"
 
 [tool.poetry]
 name = "matrix-synapse"
-version = "1.120.2"
+version = "1.121.0rc1"
 description = "Homeserver for the Matrix decentralised comms protocol"
 authors = ["Matrix.org Team and Contributors <packages@matrix.org>"]
 license = "AGPL-3.0-or-later"