Do you have a language pack installed?

Good morning Wayne

I checked and it was the Español (AR) Language Pack activated. I deleted it and everything now is working fine.

Thanks a lot.

This worked for me too. I had the English language pack installed. I'm not sure why. I think I installed it by accident when I was installing the English UK dictionary. I'm not even sure what it does. My spellchecker works in English just fine with the UK dictionary, even after removing this language pack thing. However, this does confirm that there's a bug in (presumably) the latest version of the pack or TB. (It hadn't been happening before V 91.2.0).

The problem is even worse if Thunderbird starts with the settings tab open (it opens automatically when settings where open when Thunderbird was closed last time). In this case Thunderbird freezes seconds after starting and memory usage grows no matter what you do.

I found this because I yesterday updated to 91.3.1 and after starting Thunderbird again it froze after seconds. After some time of searching I found this error description here and noticed that my "settings" tab was open when Thunderbird started...

What worked for me is open Thunderbird in safe mode (Abgesicherter Modus). To get that, hold down Shift key while starting Thunderbird. When asked, answer to continue in Safe mode. Now close the settings tab and restart Thunderbird in normal mode. Now thunderbird works again, probably until you open the settings tab next time....

This may sound like a ridiculus problem for an experienced Thunderbird user, but for somebody who just uses it for reading emails (like me) this may be a big deal.

Sorry for my bad English, I am not a native speaker ;-)

Best regards, Alex

We learned late yesterday that 91.3.1 has a regression for Macs. We anticipate this will be fixed in 91.3.2, hopefully on Tuesday.

I have the same problem with Thunderbird 91.3.2 (64-Bit) on Windows 10 21H2 (19044.1387). Uninstalling the DE and EN language packs allowed me to open preferences again. Also restarting Thunderbird in "Troubleshoot Mode" allows to open preferences (with language packs installed).

I also had this problem. Although Thunderbird was a bit tricky to get into safe mode, I figured it out. Then, without any add-ons being turned on, the problem went away. Upon further investigation and review of another posting, I removed the US language pack and restored Thunderbird to regular operations and the problem has been resolved. Thanks for the solution!