I’ve gotten the same error from a backup (previous backup was killed after stalling for two weeks) and subsequent repair attempt:
2026-01-07 21:55:52 -05 - [Error-Duplicati.Library.Main.Controller-FailedOperation]: The operation Backup has failed ConstraintException: Detected 16 file(s) in FilesetEntry without corresponding FileLookup entry
2026-01-08 20:30:51 -05 - [Error-Duplicati.Library.Main.Controller-FailedOperation]: The operation Repair has failed ConstraintException: Detected 16 file(s) in FilesetEntry without corresponding FileLookup entry
How do I fix this?
Thanks… Steve
MacOSX Tahoe 26.1
Duplicati 2.2.0.102
Macbook Pro w/M2 chip
Destination: Google Drive
I tried deleting/rebuilding the database several times, rerunning (same error), then started deleting database versions. This created a different error about missing blocks (sorry, I lost the log when I deleted the database). No one had been able to overcome the new error, from what I could find on the forum.
Anyway, I finally gave up, deleted the database, renamed the online file folder (Google Drive) to keep as an archive, and started a new backup from scratch. It took several runs over several days to create the new backup (Google only allows so many file uploads per day, so I got a log of “403” errors), but now I’ve got a current backup.
It seems like an Achilles Heel for Duplicati that it cannot recover successfully from an interruption while backing up. Any thoughts?