1) Go into the computer that we backup from, go to Services, Restart the VSS Service
2) Make sure drive is NTFS format
3) Restart Computer
if not working please try the following:
Check if Shadow storage on the source drives is not configured or not large enough?
VSS requires space allocated to each volume to be able to create and store snapshots. The steps to configure shadow copies varies between operating systems, so it’s advised to check Microsoft’s knowledgebase for the steps specific for your OS.
The steps and commands to alter the shadowstorage on any given volume are uniform across operating systems.
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%
This will resize the limit to XX percentage size for the X: drive.
We generally recommend 30% for shadowstorage size to be able to avoid most errors related to Shadow Storage.