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Firefox will not start up, how do I fix it!?


Firefox just suddenly crashed, and will not start up. I've tried restarting my computer, re installing, updating, deleting cookies/cache, run malware checks (nothing found), I dont know what else to do... HELP ME!

Additional System Details


  • User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.97 Safari/537.11

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  • Top 25 Contributor
  • Moderator
251 solutions 3015 answers

Try the Firefox Safe Mode to see how it works there. The Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

  • You can open the Firefox 4.0+ Safe Mode by holding the Shift key when you use the Firefox desktop or Start menu shortcut.
  • Or use the Help menu item and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Don't select anything right now, just use "'Start in Safe Mode" To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before using the Firefox shortcut (without the Shift key) to open it again. If it is good in the Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one.

Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.

  • Top 25 Contributor
616 solutions 4260 answers

Hello timjebsen

if you can not start firefox in safe mode even when you holding the Shift key while starting firefox(as correctly said feer56 in his reply) try to create a new profile : go from Start > Run and type %APPDATA%\Mozilla\Firefox

then find profiles.ini file and rename it to profiles.iniOLD , then when you start firefox again, a new default profile folder will be created and only a single profile, the new "default", will be listed in the Profile Manager.

This new "default" profile doesn't contain any of the profile data or settings stored in your old "default" profile folder, which still exists but is no longer accessible from the Profile Manager.

Your existing Firefox user profile data, which includes bookmarks, passwords, cookies, preference settings and added extensions, will no longer appear in the new profile but you can transfer the data from the old profile folder to the new default profile folder.

see also : Recovering important data from an old profile

thank you

Helpful Reply

Hi, thanks for the replies. I started Firefox in safe mode and it work. I disabled all my add-on's, restarted, still didn't work. In the support article disabling extensions etc. I turned off hardware acceleration and it worked! I don't know why though because i have a very powerful GPU, im guessing its the recent update by nVidia that is caused some sort of problem... Anyway thanks allot! ahh i was getting worried.

Thanks Tim

  • Top 25 Contributor
  • Moderator
251 solutions 3015 answers

Thanks for reporting back Tim!

Have a nice day.