Upgrade procedure of multi-regional deployment
Primary region: Start the upgrade from primary region and upgrade all Sitefinity CMS instances one by one. Once a Sitefinity CMS instance is upgraded and restarted, it will update the database.
Secondary region(s): Upgrade Sitefinity instances in the secondary region(s), after you have upgraded all Sitefinity CMS instances in the primary region. The upgrade of Sitefinity instances in secondary region(s) is not going to trigger database update. The databases in secondary region(s) will be updated as a result of the database replication.
For more information, see Upgrade procedure in load balanced environment.