Applying SharePoint 2016 CU's when using Always On SQL database.

Like most SharePoint patching processes you would think that it would be straight forward.

Run the following on every server in the farm sts2016-fullfile.exe reboot, run the wssloc2016-fullfile.exe then reboot. Once the patch has been applied run the SharePoint config wizard or PowerShell psconfig command on the primary application server, then each server in the farm individually after.

Not so fast if your SQL database is in an Always on configuration you have to take an extra step before running the SharePoint config wizard or PowerShell psconfig command.

The extra step is to remove the wss_UsageApplication database from the Availability Group (AG). If you do not remove this database from the AG config wizard and PowerShell both will fail.

The error that you will see in your ULS is:

Exception: The operation cannot be performed on database "WSS_UsageApplication" because it is involved in a database mirroring session or an availability group. Some operations are not allowed on a database that is participating in a database mirroring session or in an availability group. ALTER DATABASE statement failed.

Happy SharePointing