I recently migrated to openSUSE Leap 15.1. In the process, I completely lost all local duplicati files, although my remote backup set is intact.
I can use the GUI to restore from the backup using Duplicati - 2.0.4.22_canary_2019-06-30.
However, I have no idea what to do in order to restore the local files/databases needed so that I can create a backup set using the existing remote data (sftp). Nor do I know if there are any tricks to creating a new backup set using existing remote data.
Is migration supposed to leave your old files in place? Duplicati’s might be under ~/.config/Duplicati where ~ depends on what user Duplicati runs as. It might be root, it might be you, it might even be a special user.
If by “use the GUI to restore” you mean direct restore, that’s great, but to keep backing up you ideally would figure out what the migration did with your old local database. If all you can find anywhere is new, you could import or otherwise reconstruct the old backup job, then Recreate to get the DB rebuilt. It might take awhile.
If you can’t find your old job anywhere on your system, and have no prior export of it, at least you apparently know what’s most essential, e.g. passphrase and destination info. Looking at restore can infer source files.
For a thorough search of your disk drive, you could use something like the following command, run as root:
find / -mount -name Duplicati-server.sqlite
With luck you’ll find that your migration didn’t delete it, but on some OSs, the OS considers itself the owner of all things root, so if Duplicati runs as root it may get hurt. On Windows, SYSTEM has the same problem.