I started up my machine this morning, for Thunderbird 115.13 (I could've sworn that I had a later version last night, but updates and version numbers are Mozilla's problem, not mine) tells me that I can no longer use my profile with this fancy new version and need to create another one. After fuming about that idiocy for a while, I canceled the process and imported everything from my old profile. It fouled up mightily on the passwords, but I got past that obstacle course. Now, I see that my "Today Pane" is empty. Looking at the calendar, I see why: Thunderbird apparently ''pretended'' to import three calendars, but skipped all but two old events. I can create more empty calendars, but that is incredibly unhelpful. One calendar is local. One is an online ICS file published by an organization. And the third (the one that had two events picked up) is subscribed to an OwnCloud account's calendar, and may have worked. The first is obviously the most important, since I'd rather not spend time working out the database schema so that I can manually input every single event and appointment. What hoops do I need to jump through to refill my calendar? I'm running on Pop!_OS 22.04 LTS, with the Thunderbird Flatpak (commit c2e09fc595198cf5c467ddad1fab56c0be512758584e16c3b933f2410968306a according to the command-line, if that gives any clues) installed. And again, I feel like that setup used a significantly later version of Thunderbird recently, so figuring out how to undo Flatpak's decision to downgrade would also presumably solve the problem.