An Image backup fails or one of the volumes included in an Image backup fails with the following error or one similar:
Unable to back up C: The target volume is in use.
This problem may have started to happen after an Image restore was done.
When an Image backup runs, it makes changes to the base image file in the Local Storage folder. Those base image files, the (.vhd) or (.vhdx) files, need to be accessed exclusively by the Backup Agent service or else corruption in the file may occur. If another process has an handle open on any of the base image files, this error is thrown. Sometimes, the Backup Agent service may be using those files to conduct a restore and, in doing so, will trigger this error.
Check to make sure none of the following are running at the same time as the Image backup:
- A restore of an Image backup; this includes active recoveries of Rapid Recovery restores
- An Image-to-Cloud backup of the Image backup having the problem
- Another instance of the Image backup
When you have verified none of the above are running and you continue to get the "volume is in use" error, try restarting the Backup Agent service.
If none of the above fixes the issue, you may need to use a program such as Process Explorer to determine what process is using the (.vhd)/(.vhdx) files in Local Storage.