Possible causes for this error include:
- Backing up mapped network drives. You cannot use VSS on network share.
- Shadow storage on the source drives is not configured or not large enough. The shadow storage size can be checked and manually changed through command prompt:
- To check the current limit set:
vssadmin list shadowstorage
- To change the limit:
vssadmin Resize ShadowStorage /For=X: /On=X: /Maxsize=XX%
- Microsoft's native snapshot manager is only able to perform one snapshot at a time. If a snapshot process is already running when the backup job starts, then the backup job could fail. Stopping and restarting the Volume Shadow Copy service can resolve this problem. To do this, open an elevated command prompt window and run the following commands:
net stop vss
net start vss
A reboot of the server has also been known to clean up the snapshot manager correctly, should a service restart not resolve the issue.
- Multiple backup products installed could cause this error. Many backup solutions have their own proprietary snapshot manager which can cause conflicts with other backup solutions installed on the system.
- VSS snapshots have been known to fail because an advanced format drive is connected to the machine.
- Check you have all the VSS writers installed and working. On an elevated command prompt:
vssadmin list writers
If you're still having issues, please open a support ticket with your results on the above troubleshooting.