Troubleshooting VSS

What is VSS?

Volume Shadow Copy Service (VSS) is a Microsoft technology for taking consistent, point-in-time snapshots of a disk volume. A VSS Writer is an extra software plugin that detects when this action is taking place and ensures that application-specific files are in a safe state on disk. This feature allows you to invoke a single VSS Writer, or a sub-component of a single VSS Writer, and to back up only the files that it was protecting.

Important Notes

VSS snapshotting does not work over network paths. Instead of trying to snapshot over a network, install the client software onto the device which holds the original data.
VSS issues can occur if another backup software is also running, and has prevented the Comet VSS writer from working. Stop the other software to see if the issue persists.
VSS issues are often accompanied by an error code in the form of 0xXXXXXXXX. This is an externally-originating code, which will often signify why the VSS writer failed. Research this error code for solutions to the problem.

Common Problems

Issues with VSS cannot be easily solved from our end unfortunately as it runs on endpoint machines. Here are a few common issues one might see with VSS.

VSS is not running
VSS is disabled
VSS is not starting automatically
Transient issues

Common Fixes

Make sure VSS is running

Go to Control Panel > Administrative Tools > Services.
This should open a window with a long list of Windows services. Find the one that says 'Volume Shadow Copy' and double-click on it.
Set the startup type to 'automatic'
Check the service status. If it's stopped, click the 'start' button.

Dig in deeper

Open an elevated-permissions command line, and run “vssadmin list writers” to see a current list of the writers. This will highlight any which failed, as well as their own error codes. This may help troubleshoot which writer contributed to the failure or show the failure point.

Fixing transient issues

This error occurs when the machine is having difficulty holding I/O writes. It's recommended that you wait roughly 10 minutes before attempting the operation again or restarting the machine. This error may also point to a faulty hard drive.

If you are running a Hyper-V host with multiple instances, there might be a problem with leftover Storagecraft clients. Uninstalling the clients from your VM instances should fix the problem. Read more about it here.

There is a comprehensive list of solutions we use to help deal with VSS errors here.

Troubleshooting VSS