B2 Error Version Mismatch - Delete Version Fails

Does this refer to Using the Command line tools from within the Graphical User Interface? That’s prepopulated with some essential options plus others you manually added. Don’t delete them all.

Testing my B2 backup, though, deleting --passphrase got a complaint. Keeping that next run then complained about the database (because I deleted --dbpath). I’m not sure how yours timed out…
My test was on a current Duplicati, and that probably makes some difference in how things work.

There was a timeout change in January 2019 in web UI’s Commandline timeout, which increased allowable time without output from 5 minutes to 24 hours and fixed other things to avoid this error:

which looks similar to the error you had posted.

Does that refer to “Unexpected difference in fileset”, where the usual repair attempt is version delete?
The major cause of that was fixed in June 2019 in Canary, and was released in January 2.0.5.1 Beta.
You should definitely upgrade if you’re getting those, but it won’t fix an existing problem, if you’re in it.

Delete by Commandline is generally just adding the --version and clearing Commandline arguments. Anything you manually added that you suspect is irrelevant can also get deleted. Then run the delete.
Sometimes the “Unexpected difference in fileset” moves to a different version, but you’d have to try…

Backups fail with error: Object reference not set to an instance of an object was from too few options, however there are probably some other ways to get it. It’s sometimes a follow-up to some other error.