I just upgraded a laptop from maverick to natty, and saw this same problem, too (also didn't appear as a listed add-on). I was able to track down the issue to /usr/lib/thunderbird-3.1.10 having an empty directory 'extensions' instead of a symlink to ../thunderbird- addons/extensions.
I resolved the issue with: $ cd /usr/lib/thunderbird-3.1.10/ $ sudo rmdir extensions/ ; sudo ln -s ../thunderbird-addons/extensions/ ./ ** Changed in: thunderbird (Ubuntu) Status: New => Confirmed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/794151 Title: Menu does not appear in Application Menu To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/thunderbird/+bug/794151/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs