I used to use this blog as my backup brain for all sorts of things, a practice I’d gotten away from, but this one feels like it needs memorializing: what to do when the notifications stop coming on a modern (Sequoia-era) Mac, or when the widgets don’t show there.
I noticed a while ago that I could no longer quickly bring up the sidebar, which I use regularly to peek at the calendar, and that I wasn’t getting notifications showing up any more, but I couldn’t figure out why, only that there was probably some preference file corrupted somewhere. This morning I found the trick, or more specifically, where all the preference files live. Turns out that if you remove all files and directories from this folder it does the trick:
~/Library/Group Containers/group.com.apple.UserNotifications/Library/UserNotifications/Remote/defaultHat tip to Reddit for finding the right directory.
(On a general note, the good news is that there are several cases on the Mac where clearing the application state and letting the Mac rebuild it just works, and the application state is almost always saved somewhere in the Library. The bad news is that there is definitely some fragility that caused the problem in the first place and I don’t know what it is. Also, finding where in the thousands of folders in the Library that state is preserved is, to put it lightly, a problem.)