Add-on settings have been moved to Tools/Add-ons & Themes. Click the wrench icon (see picture).

ScrollAnywhere appears to have limited use in TB ([https://addons.thunderbird.net/en-US/thunderbird/addon/scroll_anywhere/ Known issues).

Some add-ons install in 91 and appear to be enabled, but they don't work.

Launch in safe/troubleshoot mode (hold Shift when starting), check 'Disable all add-ons', 'Make changes & restart'.

OK, tedious experimentation led to finally trying disabling all extensions with # firefox -safe-mode (shift didn't seem to get 'caught' on startup - I have TB ask about online status since "connected" mode when not connected is suboptimal and I travel (or used to, pre-corona)). Anyhow, the command line version works.

Disabling all extensions and restarting in normal mode yields normal operation. I can launch and quit normally - all extensions are disabled, but it is not in safe-mode.

If I enable an extension (i've tried Cardbook and sieve alone) - just that one extension - it works as expected (wrench + menu for cardbook, just menu for Sieve). I can quit normally. But on restarting with the extension enabled, the options are missing and quitting is slow and crash reports.

"WARNING: At least one completion condition is taking too long to complete. Conditions: [{"name":"Extension shutdown: sieve@mozdev.org","state":{"state":"Startup: Run manifest, asyncEmitManifestEntry(\"background\")"},"filename":"resource://gre/modules/addons/XPIProvider.jsm","lineNumber":2602,"stack":["resource://gre/modules/addons/XPIProvider.jsm:startup/<:2602","resource://gre/modules/AsyncShutdown.jsm:observe:575","chrome://global/content/globalOverlay.js:goQuitApplication:91","chrome://messenger/content/messenger.xhtml:oncommand:1"]}] Barrier: profile-change-teardown"

(the extension triggering the error is whatever one is enabled, not just sieve.

This is a pretty vanilla install from PPA via software manager on Ubuntu 21.10 (updated from 20.04).

There could easily be profile cruft as I've been using TB for quite a few years (almost decades by now). Any advice much appreciated, but I'm starting to think this is more of a bug report item than a help item.

Another user had a similar issue with add-ons. If you're reluctant to create a new profile, which is what I would recommend, it might help to remove all extension data from the profile by deleting the contents of the extensions subfolder of the profile and extension-preferences.json and extension.json in the profile.

Create a new profile from Help/More Troubleshooting, about:profiles, add an account and one add-on, say Cardbook, and see if TB open and closes without errors. At the very least, this would give more weight to a bug report, if the problem persists in the new profile.

Post a crash ID if there are any from Help/Troubleshooting, Crash Reports. An ID is a string beginning with bp-...

Indeed, I'm sure whatever the issue is, it's profile related. Too much residual cruft. I'll try backing up and then deleting my profile and testing to verify. I'll update with results.

The issue is about having the online offline / status set to ask. It is a known bug and will be fixed in an upcoming release, but at this point the fix is just making it to beta testing.

Bug 1732515 refers

@Matt, thank you, this was exactly the issue. I added some search bait to the bug report.

If you're having a similar problem and "Manual state when starting up:" is set to "Ask me for online state," try changing it to something else ("Online" worked for me.)

Edit->Preferences->Offline...->Offline Settings->Manual state when starting up:-> ◉ Online