I tried to delete using both the “delete” Commandline… option on the web UI and using the Duplicati.CommandLine.exe utility. For example, the full command I tried with the CommandLine utility was:
Duplicati.CommandLine.exe delete <target url> --passphrase=<encryption key> --dbpath=<local db path> --version=2 --no-auto-compact=true --debug-output=true --dry-run
Which returned the same error as above.
After my last post, I then tried deleting the dlist file from the destination that had the UTC time corresponding to the conflicting backup, but subsequently running a database repair replaced it on the destination. I therefore deleted it again and backed up my local DB before telling Duplicati to do a full rebuild of the local database, which I imagine should ultimately have the desired outcome.
I’ll update again once the rebuild is done.