I spent a lot of time today on this one.
I tried to backup my Sharepoint 2013 farm, full backup, via Management Shell:
Backup-SPFarm -Directory \\SERVERXXX\farm_backup\ -BackupMethod full
It did save data but always ended with an error. At the end of the log file was this gem:
FatalError: Backup failed for Object Crawl-0 (E: on SERVERXXX) failed in event OnBackup. For more information, see the spbackup.log or sprestore.log file located in the backup directory.
It was a god-damned permission problem. If you are getting this error, check your database users – open up Sql Server 2014 Configuration Manager (or the version you have) and check those:
See? Those are default:
- NT AUTHORITY\NetworkService
- NT Service\MSSQL$SQLEXPRESS
Grant them NTFS permission to the backup location and to the share (full access). Run the backup to see if the problem persists. This did it for me.