This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Firefox crashes

  • 3 replies
  • 2 have this problem
  • 8 views
  • Last reply by firetom

more options

Firefox 25 crashes on startup. The only fix I've found is to uninstall Firefox and re-install

Firefox 25 crashes on startup. The only fix I've found is to uninstall Firefox and re-install

All Replies (3)

more options

hello, you have a few malicious addons present. please try these steps:

  1. reset firefox (this wil keep your bookmarks and passwords)
  2. afterwards go to firefox > addons > extensions and in case there are still extensions listed there, disable them.
  3. finally run a full scan of your system with different security tools like the free version of malwarebytes and adwcleaner to make sure that adware isn't present in other places of your system as well.

Troubleshoot Firefox issues caused by malware

more options

Note that your System Details List shows that you have a user.js file in the profile folder to initialize some prefs on each start of Firefox.

The user.js file is only present if you or other software has created it, so normally it wouldn't be there. you can check its content with a plain text editor if you didn't create this file yourself.

The user.js file is read each time you start Firefox and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.


You can use one of these to start Firefox in Safe Mode:

  • On Windows, hold down the Shift key while starting Firefox with a double-click on the Firefox desktop shortcut
  • On Mac, hold down the Options key while starting Firefox
  • Help > Restart with Add-ons Disabled

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Firefox/Tools > Add-ons > Appearance).

  • Do NOT click the Reset button on the Safe Mode start window.
more options

Hello, I've tried to reset Firefox. As soon as press "reset" Firefox crashes. I've disabled all extensions. I've run Malwarebytes and it found many objects; all deleted. Same result though. Crash on startup.