Since a week or so, Thunderbird (68.10.0, 64 bit, running on vanilla Ubuntu 20.04) keeps popping up prompts to "Add a new address book" every 10 minutes or so.
The window looks like this:
I've restarted Thunderbird, restarted my laptop... To no avail - the popups keep coming.
How do I debug this?
Per the brilliant hint of @vanadium, simply clicking 'Next' and creating the address book stopped the popups from appearing. Probably this was some kind of update/config/setting mishap, guess we'll never know.