RabbitMQ `3.9.19` is a maintenance release in the `3.9.x` release series.
Please refer to the **Upgrading to 3.9** section from [v3.9.0 release notes](https://github.com/rabbitmq/rabbitmq-server/releases/tag/v3.9.0) if upgrading from a version prior to 3.9.0.
This release requires at least Erlang 23.2, and supports Erlang 24. [RabbitMQ and Erlang/OTP Compatibility Matrix](https://www.rabbitmq.com/which-erlang.html) has more details on Erlang version requirements for RabbitMQ.
## Changes Worth Mentioning
Release notes can be found on GitHub at [rabbitmq-server/release-notes](https://github.com/rabbitmq/rabbitmq-server/tree/v3.10.x/release-notes).
* Avoid seeding default user in old clusters that still use the deprecated `management.load_definitions` option.
This could result in an extra user, `guest` or under an [overriden default user name](https://rabbitmq.com/access-control.html#default-state), to appear
in addition to the user accounts imported from definitions.
Note that the default user with well-known name [can only connect from `localhost` by default](https://rabbitmq.com/access-control.html#loopback-users), so
this would not expose reasonably configured production nodes to remote connections.
*`rabbitmqctl set_log_level` did not have any effect on logging via [`amq.rabbitmq.log`](https://rabbitmq.com/logging.html#log-exchange) (the system exchange for logging)
Contributed by Péter @gomoripeti Gömöri (CloudAMQP).
