Periodically when Time Machine runs it will fail. The message most often refers to a file in the Library directory. Apple Support wants me to completely uninstall Norton, as they claim it creates file contention with Time Machine (see screenshot).
Has anyone else experienced this issue?
I will spare you all of the details of this, as it has gone one for over 6 months. The first solution presented by Apple was to get a new external hard drive, so I did this last February and things worked relatively well for a couple of months. When it cropped up again, we tried many things including, but not limited to both of the items you suggested (actually I have always excluded the backup disck since I went with the Mac in 2008).
As you are not Mac then I guess you cannot answer the question I asked, and I will repeat it here with a clarification as I really want to know the answer: Has anyone else experienced this issue with Time Machine backups failing?
Did you exclude backup disk from scanning?
Did you temporarily disable Norton...as test?
If Time Machine shows a message that an error occurred while preparing the backup, virus scanning software might be preventing backups from completing. Make sure you are running the latest version of the antivirus software, particularly if you have recently updated macOS. Make sure your Time Machine backup disk is excluded from virus scanning. If the issue continues, you may need to temporarily disable the antivirus software or uninstall it.
https://support.apple.com/guide/mac-help/if-a-time-machine-backup-fails-mchlb955003d/mac#:~:.
https://support.apple.com/en-us/102220
Caveat: I'm not Mac.