Merge pull request #8041 from rabbitmq/mergify/bp/v3.10.x/pr-8039

3.10.21 release notes (backport #8037) (backport #8038) (backport #8039)

release-notes/3.10.20.md

@@ -26,7 +26,7 @@ across all architectures, and the most recent TLS 1.3 implementation.
 Release notes can be found on GitHub at [rabbitmq-server/release-notes](https://github.com/rabbitmq/rabbitmq-server/tree/v3.10.x/release-notes).
 
 
-## Core Server
+### Core Server
 
 ### Bug Fixes
 

release-notes/3.10.21.md

@@ -0,0 +1,59 @@
+RabbitMQ `3.10.21` is a maintenance release in the `3.10.x` [release series](https://www.rabbitmq.com/versions.html).
+
+This series [**reaches its end of community support** on July 31st, 2023](https://rabbitmq.com/versions.html).
+
+Please refer to the upgrade section from [v3.10.0 release notes](https://github.com/rabbitmq/rabbitmq-server/releases/tag/v3.10.0)
+if upgrading from a version prior to 3.10.0.
+
+This release **requires Erlang 24.3** and supports Erlang 25.
+[RabbitMQ and Erlang/OTP Compatibility Matrix](https://www.rabbitmq.com/which-erlang.html) has more details on
+Erlang version requirements for RabbitMQ.
+
+
+### Minimum Supported Erlang Version
+
+Erlang 23 and 24 versions older than 24.3 have reached [end of support](https://www.rabbitmq.com/which-erlang.html).
+
+This release of RabbitMQ [requires Erlang 24.3.4.8](https://github.com/rabbitmq/rabbitmq-packaging/pull/35)
+or later versions. Nodes **will fail to start** on older Erlang releases.
+
+Erlang 25.3 is recommended: it offers much improved performance on ARM64 architectures, [profiling with flame graphs](https://blog.rabbitmq.com/posts/2022/05/flame-graphs/)
+across all architectures, and the most recent TLS 1.3 implementation.
+
+
+## Changes Worth Mentioning
+
+Release notes can be found on GitHub at [rabbitmq-server/release-notes](https://github.com/rabbitmq/rabbitmq-server/tree/v3.10.x/release-notes).
+
+
+### Management Plugin
+
+#### Bug Fixes
+
+ * It was impossible to return to a tab that had a filter expression
+   that was not a valid regular expressions.
+
+   Now such expressions will be used as regular text filters.
+
+   GitHub issue: [#8008](https://github.com/rabbitmq/rabbitmq-server/issues/8008)
+
+
+### HTTPS AuthN/AuthZ Backend Plugin
+
+#### Bug Fixes
+
+ * The authorization backend could run into an exception when used in
+   combination with other backends.
+
+   GitHub issue: [#7864](https://github.com/rabbitmq/rabbitmq-server/issues/7864)
+
+
+## Dependency Upgrades
+
+None in this release.
+
+
+## Source Code Archives
+
+To obtain source code of the entire distribution, please download the archive named `rabbitmq-server-3.10.21.tar.xz`
+instead of the source tarball produced by GitHub.