diff --git a/changelog.d/11849.feature b/changelog.d/11849.feature
new file mode 100644
index 000000000..6c6b57a77
--- /dev/null
+++ b/changelog.d/11849.feature
@@ -0,0 +1 @@
+Enable cache time-based expiry by default. The `expiry_time` config flag has been superseded by `expire_caches` and `cache_entry_ttl`.
diff --git a/changelog.d/11849.misc b/changelog.d/11849.misc
deleted file mode 100644
index 9561eab19..000000000
--- a/changelog.d/11849.misc
+++ /dev/null
@@ -1 +0,0 @@
-Enable cache time-based expiry by default. The `expiry_time` config flag will be superseded by `expire_caches` and `cache_entry_ttl`.
diff --git a/docs/upgrade.md b/docs/upgrade.md
index 25a86c08e..a5da0076c 100644
--- a/docs/upgrade.md
+++ b/docs/upgrade.md
@@ -117,6 +117,7 @@ Formerly, entries in the cache were not evicted regardless of whether they were
 This behavior has now changed. By default entries in the cache are now evicted after 30m of not being accessed. 
 To change the default behavior, go to the `caches` section of the config and change the `expire_caches` and 
 `cache_entry_ttl` flags as necessary. Please note that these flags replace the `expiry_time` flag in the config.  
+The `expiry_time` flag will still continue to work, but it has been deprecated and will be removed in the future.
 
 ## Deprecation of `capability` `org.matrix.msc3283.*`
 
diff --git a/synapse/config/background_updates.py b/synapse/config/background_updates.py
deleted file mode 100644
index e69de29bb..000000000