Disable and then enable shadow copies on the remote server. If there is a space limit for shadow copies, remove it.
"But it doesn't go into error until it's completely done! How can it POSSIBLY give a Writer error status at the very end of the backup process!!"
Snapshotting is freezing and then unfreezinf/commiting the snapshot. Your backups fails at the end meaning that it probably fails to commit the snapshot. Now first I would try if you can snapshot the server using the vcenter (check quiescing) and see if that works consitently and in the hours that your normal backup would run.
Is there anything else accessing the vss writers on the server in your backup window?
Is AOFO checked?
Can you please check the event viewer for further details. It should provide you with some detailed VSS writer errors.
