I see Duplicati.Library.Snapshots.UsnJournalService and wonder if that might mean you’re using –usn-policy or –snapshot-policy or both. I’m not expert in this, but I think snapshots need paths longer than would be normally seen because they get some extra components before the normally visible ones appear. Example that adds something like \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy12617 in front.
Regarding USN, there’s this fix that did not make it into 2.0.4.5 beta (which has its roots in 2.0.3.14 canary):
Issue 3311 PathTooLongException when using USNJournal #3456 (issue)
Issue 3311 PathTooLongException when using USNJournal #3456 (pull request)
Release: 2.0.4.3 (canary) 2018-11-13
- Rewrote path handling across the project to better support long paths, thanks @verhoek
Maybe more aggressive trimming to allow room for snapshot extras, or turn snapshots off, or turn USN off?
Running canary might help, but it’s less predictable. It adds known fixes (e.g. to paths) and unknown bugs.