VDR - Cannot take a quiesced snapshot of Windows 2008 R2 virtual machine error -3960

* Backup applications, such as VMware Data Recovery, fail with the error:

Failed to create snapshot for <vmname>, error -3960 (cannot quiesce virtual machine)

====================Solution=============================================

This is not a VMware issue.

This issue occurs due to a known issue with VSS application snapshots and ESXi/ESX 4.1 and later.

To work around this issue, disable VSS application-based snapshots and revert back to file system quiesced snapshots.

Notes:

• Some issues related to Windows 2008 R2 VSS application-based snapshot backups in vSphere Data Protection (VDP) have been resolved in VDP 5.1.10. For more information, see the vSphere Data Protection 5.1.10 Release Notes.
• For related information, see Troubleshooting Volume Shadow Copy (VSS) quiesce related issues (1007696) and Disabling specific VSS writers with VMware Tools (1031200).

Option 1 - Disable VSS application quiescing using the vSphere Client:

1. Power off the virtual machine.
2. Log into vCenter Server or the ESXi/ESX host through the vSphere Client.
3. Right-click the virtual machine and click Edit settings.
4. Click the Options tab.
5. Go to Advanced > General > Configuration Parameters.
6. Add or modify the row disk.EnableUUID with the value FALSE.
7. Click OK to save.
8. Click OK to exit.
9. Right-click the virtual machine and click Remove from Inventory to unregister the virtual machine from the vCenter Server inventory.
10. Register the virtual machine back to vCenter Server. For more information, see Registering or adding a virtual machine to the inventory on vCenter Server or on an ESXi/ESX host (1006160).
    
    Note: If this change is done via the command line, use vim-cmd command to reload the vmx is enough to see the changes. For more information, see Reloading a vmx file without removing the Virtual machine from inventory (1026043).
    
11. Power on the virtual machine.

Note: To configure the disk.EnableUUID parameter for VMware Data Protection (VDP), see the Resolution section in Backing up a Windows Server 2008 R2 virtual machine using VMware Data Protection 5.1 fails with the error: Execution Error: E10055:Failed to attach disk. (2035736).


Option 2 - Disable VSS application quiescing using VMware Tools:

1. Open the C:\ProgramData\VMware\VMware Tools\Tools.conf file in a text editor, such as Notepad. If the file does not exist, create it.
2. Add these lines to the file:
   
   [vmbackup]
vss.disableAppQuiescing = true
   
3. Save the file.
4. Exit the editor.
5. Restart the VMware Tools Service for the changes to take effect. Click Start > Run, type services.msc, and click OK.
6. Right-click the VMware Tools Service and click Restart.