RabbitMQ Server Files

RabbitMQ 4.1.8 is a maintenance release in the 4.1.x release series.

It is strongly recommended that you read 4.1.0 release notes in detail if upgrading from a version prior to 4.1.0.

Minimum Supported Erlang Version

RabbitMQ and Erlang/OTP Compatibility Matrix has more details on Erlang version requirements for RabbitMQ.

Nodes will fail to start on older Erlang releases.

Changes Worth Mentioning

Release notes can be found on GitHub at rabbitmq-server/release-notes.

Core Server

Bug Fixes

• Classic queue recovery on Windows could fail due to an OS-specific file locking behavior. Such failures are now retried in two more contexts.

GitHub issue: #15136

• Default queue type handling is now more defensive, avoiding an issue where attempts to declare a queue in a virtual host without any DQT set would result in a PRECONDITION_FAILED exception instead of falling back to the classic queue type for DQT.

GitHub issues: #11541, #12109, #12821, #13837

• Topic exchange binding deletions could leave orphaned trie edges in the Khepri projection, potentially causing a slowly creeping memory leak.

GitHub issue: #15025

• When a client that owns an exclusive queue disconnects and immediately reconnects and redeclares the same queue (under the same name), RabbitMQ node could delete the new queue depending on the timing of events.

Previously the only workaround was to use exclusive server-named queues for clients that exhibited this behavior. Now RabbitMQ nodes take internal owner identity into account and will remove the original queue but not the new one.

GitHub issue: #15276

• "Other ETS" and "Other system" memory metrics could end up being reported as negative values due to concurrent ETS table updates, deletion and creation on the node.

  GitHub issue: #15289

• mirrored_supervisor:child/2 could fail with a badmatch exception when a significant enough number of shovels (or federation links) was removed.

  GitHub issue: #15229

Federation Plugins

Bug Fixes

• Restored exchange federation compatibility in mixed 4.2.x/4.1.x multi-node clusters.

GitHub issue: #15252

Enhancements

• Federation links and their connections are now stopped in parallel.

This significantly improves shutdown time for nodes with many (into thousands) federation links.

GitHub issue: #15271

• Federation links no longer restart during plugin or node shutdown.

For nodes with hundreds or thousands of federation links, link recovery could significantly delay node shutdown.

GitHub issue: #15258

• Federation links use AMQP 0-9-1 connections to remote nodes (clusters).

Previously the timeout used when those connections are closed was fixed to 10 seconds. Now it is configurable via rabbitmq.conf in milliseconds:

```ini # 3 seconds for exchange federation federation.exchanges.connection_close_timeout = 3000

# 3 seconds for queue federation federation.queues.connection_close_timeout = 3000 ```

The maximum supported value is 5 seconds (5000 ms).

GitHub issue: #15268

MQTT Plugin

Enhancements

• A new configuration option, mqtt.disconnect_on_unauthorized, controls whether MQTT connections are closed upon authorization failures (for example, an attempt to consume from a topic the client has no permission for).

When set to false, the connection remains open and an appropriate protocol-level response is sent to the client instead.

The default value is true, same as RabbitMQ MQTT implementation's historic behavior.

GitHub issue: #15201