Hyper-V Quiescing Error (code 1931)
A Hyper-V backup plan terminates with the following warning: Hyper-V Quiescing Error. Cannot create application-consistent checkpoint(s) for one or more VMs with the list of virtual machines with failed application-consistent backups.
The occurrence of this warning means that the problem is on the VM side and some VMs with application-consistent issues were not processed properly. Despite the issues, the checkpoints that the Hyper-V environment managed to create were backed up.
Read about the checkpoint creation logic in the Application-Consistent Hyper-V Backups paragraph of the Application-Consistent Backups chapter
Figure Out and Fix the Problem on Guest VM
Most often, this warning occurs when some problems are on the virtual machine at the moment of checkpoint creation. You can try to figure out what happened on your own. To do this, run through the event logs of the virtual machine.
To learn how to troubleshoot VMs using the event log, read the Troubleshooting Hyper-V with Event Logs article.
Update Integration Services on Guest VM
Hyper-V Integration Services were separated from the Windows client/server versions of Windows 10/Server 2016, and updates are pulled from Windows Updates.
Any updates of Windows clients/servers earlier than Windows 10 and Windows Server 2016 must be performed manually. You can do it using the Hyper-V Manager GUI. Proceed as follows:
- Run Hyper-V Manager.
- Select the required virtual machine, right-click it.
- Click Connect.
- Select Action.
- Select Insert Integration Services Setup Disk.
- Inside the guest virtual machine, select the DVD drive with the installation files.
- Right-click the DVD drive and select Install Hyper-V Integration Services.
- As the installation completes, reboot your client/server.
- Verify the version of Hyper-V Integration Services in the Hyper-V Manager VM Summary information.
Configure Virtual Machine Checkpoints
Check the checkpoint configuration in Hyper-V Manager. To learn how to do it, read the Using checkpoints to revert virtual machines to a previous state chapter at docs.microsoft.com.
Install Integration Services
In case the Integration Services are simply not installed on the guest VM, install them manually.
This is not required for Windows Server 2016 and Windows 10 or later
For Hyper-V hosts earlier than Windows Server 2016 and Windows 10, manually install or update the Integration Services in the guest operating systems.
To install Integration Services, proceed as follows:
- Open Hyper-V Manager.
- Connect to the virtual machine. Right-click the virtual machine and select Connect.
- From the Action menu of Virtual Machine Connection, select Insert Integration Services Setup Disk. This action loads the setup disk in the virtual DVD drive. Depending on the guest operating system, you might need to start the installation manually from File Explorer.
- After the installation finishes, run the backup plan again.