Microsoft VSS Troubleshooting

Symptoms of a Volume Shadow Copy Malfunction

1. Very long (or seemingly indefinite) VSS snapshot generation time with intensive hard drive activity.
2. VSS errors reported in the Event Viewer
3. VSS errors reported by Microsoft's Volume Shadow Copy tool vssadmin
4. VSS fails to create snapshots.

VSS Repair Strategy #1

Reboot. In some cases, servers that haven't been rebooted in a while cause VSS to malfunction. As all Microsoft veterans know, you need to reboot regularly as a preventive and cleanup measure for your system.

VSS Repair Strategy #2

Open vssadmin from the command line (run cmd as administrator).

Enter vssadmin delete shadows /all  - to clean up any dead VSS snapshots. Some defect systems accumulate hundreds of VSS snapshots that persist in the system and cause Windows to become unresponsive.

Enter vssadmin list writers  - To check for errors. If you receive any errors for one VSS writer, you may need to fix that particular VSS writer. It is common to receive writer errors caused by Microsoft's Virtual Server 2005 VSS writer.

If you see a VSS writer error, try the following:

Restart the services:

  • COM System Application Service
  • Distributed Transaction Coordinator Service
  • Volume Shadow Copy Service

and also restart the affected VSS writer service, for example Volume Shadow Copy writer or Hyper-V VSS writer.

Check the Event Viewer for any additional error information logged by that VSS writer.

Run again vssadmin list writers to check if the above resolved the problem. If it didn't follow with the next strategy below:

VSS Repair Strategy #3

Uninstall all backup software on your computer, including Windows Backup if it's installed. You don't need to uninstall Servosity because Servosity doesn't contain or install any VSS writers; however, we have seen VSS writers of other backup software manufacturers cause system instability and errors.

After all other backup tools have been uninstalled, open the Registry Editor (regedit) as administrator and check the following branch: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\VSS\Providers

Underneath that key you should only find Microsoft Software Shadow Copy Provider 1.0 and no other VSS writer. If you do find another, it may be a residue registry entry of a previous backup software installation. You can save the entry by exporting the entire registry to a file (right click and select Export) and then it's safe to delete the entire branch entry underneath HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\VSS\Providers

Then reboot and try again running vssadmin list writers to confirm the problem has been resolved.

VSS Repair Strategy #4

On some systems, you can run the command vssadmin delete shadows /all to remove old VSS shadow copies. In some cases like Windows XP or Vista you need to delete old shadows using the following commands:

vssadmin Resize ShadowStorage /For=C: /On=C: /MaxSize=320MB

320MB is usually the smallest amount you can specify and will effectively delete any existing VSS snapshots on your system.

Run the vssadmin list shadows to confirm all shadows have been deletedOnce all shadows have been removed you will need to increase the max shadow storage size on your system. Use the previous command with a greater number, such as 10GB or equal to the free space on the disk.

vssadmin Resize ShadowStorage /For=C: /On=C: /MaxSize=10GB

*****Note that it is also possible to allocate shadow copy storage space on a different drive, as long as it's local:*****
vssadmin Resize ShadowStorage /For=C: /On=X: /MaxSize=200GB

VSS Repair Strategy #5

You can try to re-register all VSS and COM components by following Microsoft recommendations.

VSS Repair Strategy #6

If the PC or server you are using is a virtual machine, you need to install the latest VMware Tools (for VMware), or Virtual Machine Additions (for HyperV), on each virtual machine.

VSS Repair Strategy #7

Your computer may have a corrupt COM subscription information. Open the registry editor (regedit) and navigate to:


Then delete the Subscriptions key and reboot the machine.

A subsequent call in the command prompt should show no more errors: vssadmin list writers

This VSS repair strategy appears to work well when the System Writer is reporting an error. The Event Viewer may be reporting this or a similar error:

Writer Class Id: {e8132975-6f93-4464-a53e-1050253ae220}
Writer Name: System Writer
Writer Instance ID: {34162f4c-59ff-468e-848d-cb4b3d8dd7dc}

VSS Repair Strategy #8

Install the latest Service Packs and Updates through Windows Update. Check Microsoft's Support for hot fixes and other updates to repair VSS.


For situation where the problem persists:

After going through all steps outlined above any further Issue related to the Volume Shadow Copy (VSS) Windows services, or the Windows operating system itself should be further pursued with Microsoft support staff.