Starting unscheduled full image backup of volume “C:”…
Request of image backup failed. Reason: Creating shadow copy failed. See client log file for details.
Transferred 207 bytes - Average speed: 1.12 KBit/s
Time taken for backing up client APPLICATION-SRV: 22s
Backup failed
I’ve had this happen a few times on windows 10 clients when they are waiting for a reboot or update installation. Once you finish updates and reboot, they start working again.