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Why won't Firefox launch, the task manager shows it fluctuating from 100,000 k back down to nothing, and just repeats that forever without ever opening?

  • 6 replies
  • 7 have this problem
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  • Last reply by cor-el

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I've tried uninstalling and reinstalling, I've tried a system restore, tried manually deleting the files and reinstalling. Nothing will get Firefox to launch. No error messages, no empty tabs, it never gets that far. It just gets up to where you'd think it was about to start, then drops back down to nothing without ever having opened.

I've tried uninstalling and reinstalling, I've tried a system restore, tried manually deleting the files and reinstalling. Nothing will get Firefox to launch. No error messages, no empty tabs, it never gets that far. It just gets up to where you'd think it was about to start, then drops back down to nothing without ever having opened.

All Replies (6)

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When you removed files manually, did you remove Mozilla folders in C:\Users\<user_name>\AppData ?

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I did not, I had no idea there were files there. For some reason there somehow was created another profile once I looked there, which I deleted. Once I did that it launched just fine, well, after a few minutes. But it's no longer fluctuating without launching, it was a gradual consistent climb and then it opened. Thanks for that.

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Ok, before more complicated issues, try to start Firefox in Safe Mode.

To do it, press the Shift key and try to open Firefox in the same time. If it works, you should get a window with 2 options: Start in Safe Mode and Refresh Firefox.

Modified by Banban

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It did work in safe mode before I uninstalled it, and I did try to select refreshing it as suggested on the troubleshooting page, but I don't know if it worked. Not in that it still failed to launch even after the refresh, but I'm not sure the refresh itself even completed since it said "almost done" for about ten minutes and I think it got closed out somehow, maybe during the system restore or something.

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According to support article, you should read Profile Manager - Create, remove or switch Firefox profiles to start the Profile Manager and removing your profile.

If Profile Manager doesn't start, we will consider other ways.

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It is possible that your firewall or other security software blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full, unrestricted, access to install for Firefox and the plugin-container process and the updater process.

See:

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) as a test.


You can check if you can start Firefox in Safe Mode by holding down the Shift/Options key.