Seems it's not a bug in thunderbird, but a bug in enigmail package (and possibly all extensions packages that uses thunderbird directory instead of thunderbird-addons) - it has '/usr/lib/thunderbird/extensions' directory, but should have '/usr/lib/thunderbird-addons/extensions'. So, when installation of new version of enigmail happens earlier than installation of thunderbird itself - this bug appears.
Looking wide I have to say that /usr/lib/thunderbird-addons directory becomes meaningless now, when we have one /usr/lib/thunderbird directory (without version suffix). May be it's time to make it just a symlink to /usr/lib/thunderbird (for compatibility reasons)? ** Also affects: enigmail (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/995054 Title: thunderbird looses langpacks after upgrade To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/enigmail/+bug/995054/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs