The disk that stores the duplicati databases ran out of disk space. After resolving the disk space issues, I began getting errors on the backups so I tried to recreate the database.
When I try to recreate, I get this error: Unexpected difference in fileset 15, found 135249 entries, but expected 135251
Not sure what has happened, but I would guess that you can simply delete backup version 15 and then move on.
There is no direct UI for removing a specific version, but you can use the commandline (there is a UI for that) where you can use the “delete” command with the argument “15” to remove it (you need to supply the --dbpath setting from the original backup, but you can remove the other options).