Confirm that the VM that the files are being restored from was using one the following filesystems.
1. Clear all temporary files from “C:\Users\<serviceaccount>\AppData\Local\Temp\”
Note: When the Veeam Backup Service account is ‘local system’, the temporary directory used is C:\Windows\Temp.
2. Open an Administrator Command Prompt and run the following commands:
(The installation path for Veeam if it was upgraded from 6.5 is: C:\Program Files\Veeam\Backup and Replication\)
(With Veeam v9 the operation must be performed on a Mount Server under the path: C:\Program Files\Common Files\Veeam\Backup and Replication\Mount Service)
cd “C:\Program Files\Veeam\Backup and Replication\Backup”
3. Confirm that the account being used for the Veeam Backup Service has the "Perform volume maintenance tasks" right assigned to it. This can be located within the group policy (gpedit.msc) under:
Computer Configuration>Windows Settings>Security Settings>Local Policies>User Rights Assignment
4. Reboot the Veeam server