How to enable Windows Server Backup support for the Hyper-V VSS Writer

In order to enable VSS based backups of Hyper-V VMs using Windows Server Backup, you must add the following registry keys to register the Hyper-V VSS Writer with Windows Server Backup. Note that the WindowsServerBackup key is not created when installing the Windows Server Backup feature. This key must be created manually.

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT
\CurrentVersion\WindowsServerBackup\Application Support\{66841CD4-6DED-4F4B-8F17-FD23F8DDC3DE}

Once you have the keys listed above created, you will need to create a String Value with the following.

Name: Application Identifier
Type: REG_SZ
Value: Hyper-V

When complete, the keys should resemble the following:


Windows Server Backup only supports volume based backups. When backing up virtual machines, you must select all volumes where VM related files are present.

For example, if you are using the default location for storing virtual machine configuration  (C:\ProgramData\Microsoft\Windows\Hyper-V\Virtual Machines) yet the VHD is stored on another volume, you must select both volumes in the backup.

When initiating recovery, select “Application Restore” and choose Hyper-V.  You must use this method otherwise you will not be allowed to replace files for running VMs. As part of the restore, existing VMs will be turned off and deleted. The VMs that you restore will be registered with Hyper-V.

There are some limitations and expected behavior that you should be aware of.

1: Virtual machines that contain dynamic disks in the guest operating system cannot be backed up using VSS. Only offline backups are supported. The other alternative is to backup the virtual machine using backup software inside the guest operating system as you would with a physical machine.

2: Virtual machines that do not have support for VSS Backups, such as Windows 2000, Windows XP, or virtual machines without Integration Services installed, will enter a saved state while the snapshot is taken and restore once the snapshot is complete.  You will also experience the same behavior if the backup component from Hyper-V Integration Services is disabled as shown below.



3: When performing a recovery from backup, the entire volume(s) must be restored. Individual VM restores are not supported with Windows Server Backup.

4: If the virtual machine contains 2 or more snapshots, the restore will fail. To workaround this issue:

A.   If the VM is running, turn off and delete the virtual machine.
B.   Select the “Files and Folder” recovery option to restore the snapshots folder.
       By default, this is located at
       but is configurable per VM.
C.   Select the individual snapshot folders to restore.
D.   Once this is complete, initiate the “Application” recovery option to restore the volume.

Rob Hefner
Support Escalation Engineer
Microsoft Enterprise Platforms Support