Rails applications that use ActiveRecord objects in their cache may experience an issue where the entries cannot be invalidated if all of these conditions are true:
They are using Rails 5.2+
They have configured config.active_record.cache_versioning = true
They are using a cache that is not maintained by Rails, such as dalli_store
In this post, we discuss the background to a change in the way that cache keys work with Rails, why this change introduced an API incompatibility with third-party cache stores, and finally how you can find out if your app is at risk and how to fix it.