VM Application aware back up fails on a 2012 R2 DC Guest (Event Id: 8229 VSS seen on Guest) on a 2016 host

This one was odd and I don't have the full history but got passed a call were Altaro was warning that an application aware backup was not possible and it was falling back to crash consistent.  As it was a DC server ideally it should be application aware.

The DC was Windows 2012 R2 running on 2016 Hyper-V server.  All the settings looked good and running Windows backup within the guest was able to backup with no issues.

Every time Altaro tried to take a back up with application the guest logged an event with id 8229 and an error code of 0x800423f4.

This appears to be an issue with the integrated servers triggering the backup within the guest and has an update that resolves the issue.  Has to be installed on the guest.

KB5001088: "BackupComplete" event message is not received when backing up Windows Server 2012 or Server 2012 R2 VMs residing on Windows Server 2016 or Server 2019 host (microsoft.com)