Summary

There is no current method to perform a Zero Downtime upgrade for Crowd as there is for Jira (ex: Managing zero downtime upgrades). This is particularly important for Crowd instances that have several Atlassian products connected to Crowd, leaving the applications vulnerable to downtime while the upgrade process is running.

Workaround

If a customer would like to proceed with the upgrade without having to shut down the application, they will have to restore an XML backup to the new version of Crowd, ensure the new instance is working correctly, and then point all the apps to the new version. This would be a similar process to Migrating Crowd Between Servers.