SharePoint 2013 backup fails – Object Crawl-0 (E: on WW-SP) failed in event OnBackupComplete

Today I encountered the following failure message when running a manual backup of my SharePoint 2013 environment using Central Administration:

Object Crawl-0 (E: on WW-SP) failed in event OnBackupComplete. For more information, see the spbackup.log or sprestore.log file located in the backup directory.

I opened the spbackup.log file and searched for the string ‘error’ which contained several entries all relating to the SQL databases.  I then realised that I was backing up to a local path as opposed to a UNC path.  I change the job to backup to a UNC path and the backup completed successfully.