Ok, this is somehow extensions related. Starting with --safe-mode results in a working version.
In my case I pinned it down to the firetray addon. Since it is unmaintained, I guess this is a won't fix. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to firefox in Ubuntu. https://bugs.launchpad.net/bugs/1575708 Title: Firefox 46 works only with fresh profile Status in firefox package in Ubuntu: New Bug description: A freshly updated firefox (to 46) does not work anymore if there is already a firefox profile. Basically everything is broken: sessions, menus even browsing by typing in a web address. As a work around (sort of), one can delete the profile (~/.mozilla) and start fresh ... and lose all settings, extensions etc. Or downgrade until this is fixed. I get this issue on two machines running a fully updated xubuntu trusty. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1575708/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp