Example

"Unable to release guest. Error: VSSControl: Failed to freeze guest over Hypervisor API, wait timeout
Error: VSSControl: Failed to freeze guest over Hypervisor API, wait timeout."

"Failed to prepare guest for hot backup. Error: VSSControl: Backup job failed. Cannot create a shadow copy of the volumes containing writer's data. A VSS critical writer has failed. Writer name: [Microsoft Exchange Writer]. Class ID: [{}]. Instance ID: [{}]. Writer's state: [VSS_WS_FAILED_AT_FREEZE]. Error code: [].
Error: VSSControl: Backup job failed. Cannot create a shadow copy of the volumes containing writer's data. A VSS critical writer has failed. Writer name: [Microsoft Exchange Writer]. Class ID: [{}]. Instance ID: [{}]. Writer's state: [VSS_WS_FAILED_AT_FREEZE]. Error code: []."

Threshold

Errors occurred during Microsoft VSS Processing.

Summary

During the application aware processing there was an issue with Microsoft Volume Shadow Service processing the data on the system.

Solution

Typically a reboot of the target virtual machine will resolve most issues.

Check Event Viewer on the machine for any Volume Shady Copy related issues and resolve.

Below are some typical issues that you might run into.

Check that the VSS Writers are not in a failed state

  • From an administrative command prompt run:
    • vssadmin list providers
  • Confirm all writers are showing:
    • State: 1 Stable
    • No Error
  • If any errors are found, please follow normal troubleshooting

Check that there is enough space dedicated for VSS

  • Right click on any listed Hard Drives on the system
  • Click Configure Shadow Copies
  • The Shadow Copies window lists all drives on the system.
  • Select the drives and verify there is enough space dedicated to VSS

Validate the User Account Control is completely disabled via registry

  • Edit the following registry key and set to 0.
    • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\EnableLUA
  • Immediately reboot the Guest OS.
    • If not done immediately, the settings will revert.