# v5.2.1

## Enhancements

- [#11487](https://github.com/emqx/emqx/pull/11487) The bcrypt work factor is limited to the range 5-10, because higher values consume too much CPU resources.
  Bcrypt library is updated to allow parallel hash evaluation.

- [#11532](https://github.com/emqx/emqx/pull/11532) Improve some error reasons when parsing invalid packets.

- [#11568](https://github.com/emqx/emqx/pull/11568) Added support for defining templates for MQTT 5.0 publish properties and user properties in Republish rule action.

## Bug Fixes

- [#11493](https://github.com/emqx/emqx/pull/11493) Examples and documentation for /api/v5/publish bad request response have been fixed. Previously the documentation example said that the bad request response could return a list in the body which was not actually the case.

- [#11499](https://github.com/emqx/emqx/pull/11499) Upgrade Erlang/OTP to 25.3.2-2

  Erlang/OTP 25.3.2-2 excludes sensitive data from mnesia_hook log message.

- [#11506](https://github.com/emqx/emqx/pull/11506) Don't download a trace log file if it is empty.

  After this fix, GET `/api/v5/trace/clientempty/download` returns 404 `{"code":"NOT_FOUND","message":"Trace is empty"}`
  If no events matching the trace condition occurred.

- [#11522](https://github.com/emqx/emqx/pull/11522) Improved error message for rule engine schema registry when schema name exceeds permissible length.

- [#11531](https://github.com/emqx/emqx/pull/11531) Fixed issue where authorization cache cleaning cli was not working properly for specific client ID.

- [#11564](https://github.com/emqx/emqx/pull/11564) Fix cluster partition autoheal functionality.
  Implement autohealing for the clusters that split into multiple partitions.

- [#11568](https://github.com/emqx/emqx/pull/11568) Fixed an issue where an ill-defined built-in rule action config could be interpreted as a custom user function.

- [#11630](https://github.com/emqx/emqx/pull/11630) Fixed an issue where the core node could get stuck in the `mria_schema:bootstrap/0` state, preventing new nodes from joining the cluster.