When you check the event log of de server you see a event 517.
Name: Microsoft-Windows-Backup
Source: Microsoft-Windows-Backup
Date: date
Event ID: 5
Task Category: None
Level: Error
Keywords:
User: username
Computer: computer name
Description:
The backup operation that started at time has failed with following error code ‘2155347997’ (The operation ended before completion.). Please review the event details for a solution, and then rerun the backup operation once the issue is resolved
This a now Bug check KB2182466 you can download the hotfix here KBHotfix