Welcome to the forum @CAREFiSH
Is this an initial backup problem or an ongoing backup that failed? Is this a basic Windows install?
That’s not the whole message (there are examples in the other reports). Do you have more lines?
Getting back to question of initial backup versus ongoing that died. It may take longer to investigate.
Advantage of investigating is there’s a chance something may be learned to avoid future problems.
Did you try The PURGE command? Latest version (0) could be the starter. Add more if necessary.
Besides the low-level DB DELETE command plan, this seems like one of the confirmed cleanups.
So you’ve got some sort of browser? That may come in handy to look around further at the error.
Creating a bug report would be nice to allow someone else to examine, but names are redacted.
So you have a longer message with source file names? I don’t need names, but you do to purge.
Can you post more, redacting names as you wish? Try About → Show log → Live → Warning.
Fatal backup errors often wind up in server log at Home → About → Show log. Click error lines.