We will upgrade RabbitMQ and Erlang versions on shared servers "chicken" and "roedeer".
For minimal disturbance, remember to always configure your clients to automatically reconnect on connection loss. Please do a full reload (cmd-shift-r) if the management interface is not accessible after the upgrade has been completed.
If you can't allow any scheduled downtime we recommend you to move to a new dedicated cluster via queue federation, as explained here: https://www.cloudamqp.com/blog/2015-07-08-migrate-between-plans-rabbitmq-queue-federation.html
Messages in priority queues will not survive an upgrade between RabbitMQ version 3.6 to 3.7. It is therefore important that any messages in priority queues are consumed or that you move to a dedicated instance prior to this maintenance.