Enhancements

• #12983 Add new rule engine event $events/client_check_authn_complete for authentication completion event.

• #13180 Improved client message handling performance when EMQX is running on Erlang/OTP 26 and increased message throughput by 10% in fan-in mode.

• #13191 Upgraded EMQX Docker images to run on Erlang/OTP 26.

  EMQX had been running on Erlang/OTP 26 since v5.5 except for docker images which were on Erlang/OTP 25. Now all releases are on Erlang/OTP 26.

• #13242 Significantly increased the startup speed of EMQX dashboard listener.

Bug Fixes

• #13156 Resolved an issue where the Dashboard Monitoring pages would crash following the update to EMQX v5.7.0.

• #13164 Fixed HTTP authorization request body encoding.

  Before this fix, the HTTP authorization request body encoding format was taken from the accept header. The fix is to respect the content-type header instead. Also added access templating variable for v4 compatibility. The access code of SUBSCRIBE action is 1 and PUBLISH action is 2.

• #13238 Improved the logged error messages when an HTTP authorization request with an unsupported content-type header is returned.

• #13258 Fix an issue where the MQTT-SN gateway would not restart correctly due to incorrect startup order of gateway dependencies.

• #13273 Fixed and improved handling of URIs in several configurations. The fix includes the following improvement details:

  • Authentication and authorization configurations: Corrected a previous error where valid pathless URIs such as https://example.com?q=x were mistakenly rejected. These URIs are now properly recognized as valid.
  • Connector configurations: Enhanced checks to ensure that URIs with potentially problematic components, such as user info or fragment parts, are no longer erroneously accepted.

• #13276 Fixed an issue in the durable message storage mechanism where parts of the internal storage state were not correctly persisted during the setup of new storage generations. The concept of "generation" is used internally and is crucial for managing message expiration and cleanup. This could have manifested as messages being lost after a restart of EMQX.

• #13291 Fixed an issue where durable storage sites that were down being reported as up.

• #13290 Fixed an issue where the command $ bin/emqx ctl rules show rule_0hyd would produce no output when used to display rules with a data integration action attached.

• #13293 Improved the restoration process from data backups by automating the re-indexing of imported retained messages. Previously, re-indexing required manual intervention using the emqx ctl retainer reindex start CLI command after importing a data backup file.

  This fix also extended the functionality to allow exporting retained messages to a backup file when the retainer.backend.storage_type is configured as ram. Previously, only setups with disc as the storage type supported exporting retained messages.

• #13140 Fixed an issue that caused text traces for the republish action to crash and not display correctly.

• #13148 Fixed an issue where a 500 HTTP status code could be returned by /connectors/:connector-id/start when there is a timeout waiting for the resource to be connected.

• #13181 EMQX now forcefully shut down the connector process when attempting to stop a connector, if such operation times out. This fix also improved the clarity of error messages when disabling an action or source fails due to an unresponsive underlying connector.

• #13216 Respect clientid_prefix config for MQTT bridges. Since EMQX v5.4.1, the MQTT client IDs are restricted to a maximum of 23 bytes. Previously, the system factored the clientid_prefix into the hash of the original, longer client ID, affecting the final shortened ID. The fix includes the following change details:

  • Without Prefix: The behavior remains unchanged. EMQX hashes the long client IDs (exceeding 23 bytes) to fit within the 23-byte limit.
  • With Prefix:
    • Prefix ≤ 19 bytes: The prefix is retained, and the remaining portion of the client ID is hashed into a 4-byte space, ensuring the total length does not exceed 23 bytes.
    • Prefix ≥ 20 bytes: EMQX will not attempt to shorten the client ID, fully preserving the configured prefix regardless of length.