Incompatible Changes between EMQX 5.x and EMQX 6.0

Deprecated Packages

• #15939 Stopped releasing packages for systems that have already reached end-of-life:

  • Debian 10 (Buster)
  • Enterprise Linux (CentOS) 7
  • Ubuntu 18.04
  • Ubuntu 20.04
  • macOS 13 (Ventura)

• #16050 Stopped releasing packages for Amazon Linux 2. It will reach end-of-life on June 30, 2026.

Durable Sessions

If the durable sessions feature was not enabled before, you can ignore this section.

In EMQX 6.0, the internal representation of durable sessions and their messages has changed. Clusters previously running on version 5.x with durable sessions enabled must be recreated from a clean state when upgrading to 6.0.

For detailed upgrade instructions, see the rolling upgrade documentation.

• #15496 The state of durable sessions has been migrated from Mnesia to a new database built on EMQX durable storage.
  • As a result, all durable session states created before 6.0.0 will be lost during the migration.
  • This change resolves potential session state corruption caused by Mnesia’s limited transaction isolation (see #14039).
  • It also improves the performance and scalability of durable sessions through sharding and a more efficient data representation.

Will Message Behavior

Authorization checks for durable sessions are now performed at the moment of client disconnection to determine whether the will message may be published.

Previously, these checks were deferred until after the configured Will-Delay-Interval had expired.

Configuration Changes

Durable Sessions

• durable_storage.messages.n_sites parameter has been renamed to durable_storage.n_sites. This parameter has become common for all durable storage.
• durable_storage.sessions and durable_storage.timers have been added.
• #15734 Improved the reliability and throughput of durable sessions.

Durable Storage

• durable_storage.messages.n_sites has been renamed to durable_storage.n_sites, which now applies to all durable storage types.
• Added new configuration entries for durable_storage.sessions and durable_storage.timers.

RocketMQ

• #15635 The parameters.strategy field no longer accepts key templates (which previously implied the key_dispatch strategy). Instead, set parameters.strategy = key_dispatch explicitly and specify the key template in parameters.key.

Platform Support

• #15613 Discontinued package builds for Debian 10.

Rate Limit

• #15743 Listener connection rate limits (max_conn_rate and max_conn_burst) are now enforced per listener rather than per acceptor, restoring the behavior before 5.9.0. As a result, configurations from versions 5.9.0, 5.9.1, and 5.10.0 are incompatible: the specified rate values must be scaled up by the number of acceptors configured for each listener to preserve the same effective limits.