Microsoft Hyper-V VSS Writer' writer status is invalid.
Last month we upgraded from Server 2012 to Server 2019 with one VM (domain controller). The Hyper-V scheduled backup ran fine on Server 2012, but on Server 2019 it always fails with the following error:
'Microsoft Hyper-V VSS Writer' writer status is invalid. Try again later or see Event Log for more information. State: FailedAtPrepareSnapshot, Failure: WriterErrorRetryable
When I check the VSS writers (command prompt, VSSadmin list writers), Hyper-V VSS Writer has State:  Stable and Last Error: No Error.
I found a note in https://www.msp360.com/resources/blog/troubleshooting-vss-volume-shadow-copy-issues/
regarding domain controllers:
MSP360 Backup uses VSS Microsoft Service. During a backup of a Domain Controller issues might occur with VSS. If it happens, disable VSS in MSP360 Backup on the Backup Wizard step and retry the backup. If that doesn't help, please contact our support team.
I've gone through the Hyper-V Backup Wizard but I'm not seeing an option to disable VSS.
Any ideas? Scheduled file backups run fine, but I'm having to run Hyper-V backups manually.