Having finished my articles this morning, I figured it was time for an apt-get dist-upgrade on the laptop to ensure I was running the latest versions of everything. A quick download and install later, and it was time to reboot.
At which point Firefox broke completely. No starty, no error – even when launched from the shell.
It’s taken me a little while, but I’ve tracked down the culprit: the Prism plugin. If you’ve got Prism – a stand-alone Mozilla-based browser for creating desktop-style access to web apps – then the chances are you’ll be bitten by this bug, as installing Prism automatically installs the plugin into Firefox.
Thankfully, the fix is simple: go to Tools -> Add-Ons and disable Prism.
What’s that? You can’t load Firefox in order to disable the Prism plugin? There’s a fix for that, too. Load a shell (Applications -> Accessories -> Terminal) and type:
cd ~/.mozilla/firefox ls
That’ll give you a listing of the directory – with a single entry, which is your profile folder. Use cd to change to this directory, then type:
rm compatibility.ini
Once you’ve done that, Firefox should start fine and you’ll be able to disable the add-on.
If you’re curious, there’s a bug filed on Launchpad over here.