emqx4.3/changes/ee/fix-14015.en.md

Previously, if a Kafka/Confluent/Azure Event Hub Producer action with disk buffering had queued messages and was restarted, the queued messages were not sent until a new message arrived. For actions that have a fixed topic (i.e., the topic does not contain any placeholders), this was fixed.

Prior to EMQX 5.7.2, when using a Kafka/Confluent/Azure Event Hub Producer action with disk buffering, its files were stored in a different directory structure. Now, when starting such an action, if an old disk buffer directory is detected, it'll be renamed to the newer structure to avoid losing data.