When you try to perform File Level Restore via the Veeam Backup Enterprise Manager UI, the following error occurs:
Error occurred during the FLR job execution
Failed to mount disk. Check free disk space on backup server
The following entries can be seen in the Svc.VeeamBES.log:
[timestamp] <57> Info Mapping mounted drives.
[timestamp] <57> Info Trying path [C:\Users\user\AppData\Local\Temp\xxxx]
[timestamp] <57> Error Failed to map mounted drives.
[timestamp] <57> Error Failed to mount disk. Check free disk space on backup server. (System.Exception)
[timestamp] <57> Error bei Veeam.Backup.EnterpriseServices.CFLRRestoreTask.MapMountedDrives(String[] mountedDrives)
However, if you launch File Level Restore from the Veeam Backup console, it is completed successfully.