FATAL config_mismatch (4044447)

Error received similiar to:
An internal error occurred during execution, please contact Vizioncore support if the error persists. Error Message: Backup: 'phys:/vmfs/volumes/4b211533-752144b2-e30c-00265526457e/vm-XXX/vm-XXX-flat.vmdk' failed.
FATAL config_mismatch config doesn't match parent (at var_open_write_base:262)
 

There are a couple of possible causes for that error. Has the VM's disk/disks been resized recently? If they have been go to the My Repository view and try deleting all of the backup archives that were created before the resize. Another possible cause would be a 0k .var file left behind from a previous failed backup. To resolve this delete the incomplete backups and retry the job.