This may not be a text book method to resolve VSS backup issues but it seemed to have worked on few of the Windows 2003 servers we had issues while performing a Volume Shadow Copy backup. If you have issues while performing a shadow copy backup using NT backup utility, it might fail reporting:
Error returned while creating the volume shadow copy:0xffffffff
VSS backup mainly depends on the state of the VSS Writers on a particular Windows server. To check the writer status, run the following command:
VSSADMIN LIST WRITERS
This should display the writers along with its instance IDs and status like Delayed, Retrying, Failed, etc. If this command executes successfully and returns nothing then it indicates the writers are not being picked up or recognized and hence VSS backups would fail. If the command prompt appears to freeze and does not return any output, it indicates that there is some issue with the VSS writers on that server.
To troubleshoot this you could do the following on the Windows server:
Run CHKDSK and to figure out if there is any issue with the file system, and if yes, then run the same in read-write mode
Reboot the server and try the “VSSADMIN LIST WRITERS” command again.. still doesn’t look good?
Open registry editor (Regedit) and delete the following
(Delete the Subscriptions directory). It would be good to have a back up of this directory before deleting.
Once this directory is deleted, reboot the server and the directory which was deleted will get regenerated along with its keys and sub-directories.
VSSADMIN LIST WRITERS should now display all the writers and you could test functioning of VSS backup by backing up the System State using the NT Backup.
If the backup still does not happen then perhaps you may want to troubleshoot further and post a note below to let us know how you resolved your issue regarding backing up a Volume Shadow Copy. However from my experience, the above tweak mostly does the trick.