I have a fairly new 2012 R2 server with Essentials role installed. I just finished setting it up exactly as I like with clients connected and backing up to a storage space on the server. I bought a new eternal USB 3.0 HDD and just set up the server backup. I used the wizard in the Dashboard to create the backup job, excluding only the storage spaces drive. When I attempt to run the backup job, it always fails with error code 0x80780049 in the event log. I have run chkdsk on C drive with no issues found. During the backup wizard, I allowed it to format the new external drive. If I watch the job run, it will get to 18%, and then jump to 100% and then say unsuccessful. After looking at other posts on TechNet, I have tried to shrink the drive, recreate the job, and even uncheck all but drive C. No change. I also tried running the job via elevated command line, "wbadmin start backup". When it reached 18%, it would repeat that output several times then fail.
Any ideas would be appreciated.