I did the upgrade today and also found that it worked the first time I started it but crashed every time after that. I ran the following, which fixed the problem.
sudo apt remove thunderbird-locale* rm .thunderbird/{profile name}/extensions/langpack-en...@thunderbird.mozilla.org.xpi sudo apt install thunderbird-locale-en -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1901829 Title: thunderbird fails to open, xml parse error To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/thunderbird/+bug/1901829/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs