We have a server with Windows Server 2012 R2 Essentials installed. Backup is set up using the Windows Server Essentials Dashboard to back up to a USB drive. Every second day, the backup completes successfully. On the days in between, backup fails. This pattern seems absolutely consistent.
On the days when it fails, the Application Event Log contains an error 517 from source "Backup" with detail "The backup operation that started at '?2014?-?11?-?15T01:00:09.561288500Z' has failed with following error code '0x800700EA' (More data is available.). Please review the event details for a solution, and then rerun the backup operation once the issue is resolved."
The above error is logged around 2 minutes after the start of the backup. No other errors appear in the Application Event Log.
Backup log files are created in %windir%\logs\windowsserverbackup on the days when the backup completes successfully. Nothing is created in there on the days when it fails.
Any ideas as to what's going on here, and how it might be fixed, please?