Re-generate changelog.

CHANGES.md

@@ -21,6 +21,7 @@ Bugfixes
 - Fix a bug introduced in Synapse 1.7.2 whereby background updates are never run with the default background batch size. ([\#12157](https://github.com/matrix-org/synapse/issues/12157))
 - Fix a bug where non-standard information was returned from the `/hierarchy` API. Introduced in Synapse v1.41.0. ([\#12175](https://github.com/matrix-org/synapse/issues/12175))
 - Fix a bug introduced in Synapse 1.54.0 that broke background updates on sqlite homeservers while search was disabled. ([\#12215](https://github.com/matrix-org/synapse/issues/12215))
+- Fix a long-standing bug when a `filter` argument with `event_fields` which did not include the `unsigned` field could result in a 500 error on `/sync`. ([\#12234](https://github.com/matrix-org/synapse/issues/12234))
 
 
 Improved Documentation

changelog.d/12234.bugfix

@@ -1 +0,0 @@
-Fix a long-standing bug when a `filter` argument with `event_fields` supplied but not including the `unsigned` field could result in a 500 error on `/sync`.