Final error: 0x8004230f - 0x8004230f (2147754767).
V-79-10000-11226 - VSS Snapshot error. The Microsoft Volume Shadow Copy Service (VSS) snapshot provider selected returned: "Unexpected provider error". Ensure that all provider services are enabled and can be started. Check the Windows Event Viewer for details.
This error can occur if the System Reserve Partition is offline.
To resolve the issue, perform the following:
1) Run VSSADMIN LIST WRITERS from the command line and reboot if writers are in a failed state
2) Rerun backup, if same error occurs proceed to step #3
3) From the command prompt run DISKPART with the following commands:
C:\>DISKPART
C:\DISKPART> List volume
C:\DISKPART> Select volume
C:\DISKPART> Online volume (if volume is showing offline)
To prevent volume from going offline in the future, refer to Microsoft KB#2419286
https://support.microsoft.com/kb/2419286
C:\DISKPART> automount enable
C:\Diskpart> exit
4) Reboot server and run DISKPART again to ensure the partition is not offline again
5) Rerun backup to confirm