# v5.6.1

## Bug Fixes

- [#12759](https://github.com/emqx/emqx/pull/12759) Do not save invalid uploaded backup files.

- [#12766](https://github.com/emqx/emqx/pull/12766) Rename `message_queue_too_long` error reason to `mailbox_overflow`

  `mailbox_overflow` is consistent with the corresponding config parameter: `force_shutdown.max_mailbox_size`.

- [#12773](https://github.com/emqx/emqx/pull/12773) Upgrade HTTP client libraries.

  The HTTP client library (`gun-1.3`) incorrectly appends a `:portnumber` suffix to the `Host` header for
  standard ports (`http` on port 80, `https` on port 443). This could cause compatibility issues with servers or
  gateways performing strict `Host` header checks (e.g., AWS Lambda, Alibaba Cloud HTTP gateways), leading to
  errors such as `InvalidCustomDomain.NotFound` or "The specified CustomDomain does not exist."

- [#12802](https://github.com/emqx/emqx/pull/12802) Improve cluster discovery behaviour when a node is manually removed from a cluster using 'emqx ctl cluster leave' command.
  Previously, if the configured cluster 'discovery_strategy' was not 'manual', the left node might re-discover and re-join the same cluster shortly after it left (unless it was stopped).
  After this change, 'cluster leave' command disables automatic cluster_discovery, so that the left node won't re-join the same cluster again. Cluster discovery can be re-enabled by running 'emqx ctl discovery enable` or by restarting the left node.

- [#12814](https://github.com/emqx/emqx/pull/12814) Handle several errors in `/clients/{clientid}/mqueue_messages` and `/clients/{clientid}/inflight_messages` APIs:

  - Internal timeout, which means that EMQX failed to get the list of Inflight/Mqueue messages within the default timeout of 5 s. This error may occur when the system is under a heavy load. The API will return 500 `{"code":"INTERNAL_ERROR","message":"timeout"}` response and log additional details.
  - Client shutdown. The error may occur if the client connection is shutdown during the API call. The API will return 404 `{"code": "CLIENT_SHUTDOWN", "message": "Client connection has been shutdown"}` response in this case.

- [#12824](https://github.com/emqx/emqx/pull/12824) Make sure stats `'subscribers.count'` `'subscribers.max'` countains shared-subscribers.
  It only contains non-shared subscribers previously.

- [#12826](https://github.com/emqx/emqx/pull/12826) Fixed an issue that prevented importing source data integrations and retained messages.

  Before the fix:

  - source data integrations are ignored from the backup file
  - importing the `mnesia` table for retained messages are not supported

- [#12843](https://github.com/emqx/emqx/pull/12843) Fixed `cluster_rpc_commit` transaction ID cleanup procedure after `cluster leave` on replicant nodes.
  Previously, the transaction id of the core node would be deleted prematurely, blocking configuration updates on the core node.

- [#12885](https://github.com/emqx/emqx/pull/12885) Fixed an issue when users were not able to see the "Retained Messages" under the "Monitoring" menu in the admin dashboard.

"Retained messages" backend API uses `qlc`, and `qlc` uses `file_sorter` that puts temporary files in the working directory by default, which is not writable by emqx user since 58d0f04.

This patch fixes this by making `/opt/emqx` directory owned by `emqx:emqx`.