An operation in Acronis Backup 12.5 or Acronis Backup Cloud fails with "The activity has failed due to a restart of the service." or "The activity has failed due to an unexpected machine reboot or the backup process was terminated."
The issue could be caused by:
Machine reboot during the operation
To determine the exact root cause:
If the error was caused by a machine reboot, consider changing Acronis operations schedule or reboot schedule.