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Firefox states it is already running yet won't open even after I uninstalled and reinstalled

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Hi,

I was having problems with Mozilla when I'd go to Facebook it would show the page but within seconds I would get check6 (can't remember the rest) error page.

So I went to help, restart Firefox. It was at this for about an hour and I knew there was a problem so chose to end process in task manager.

Since then I haven't been able to open Firefox: "Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system".

I uninstalled Firefox using Revo Uninstaller and deleted all leftover files, restarted my computer and installed Firefox, but the problem still remains.

I tried looking through previous questions and noticed I do no have a profile folder which may be needed to delete a lock file....

Any help much appreciated! thanks

Hi, I was having problems with Mozilla when I'd go to Facebook it would show the page but within seconds I would get check6 (can't remember the rest) error page. So I went to help, restart Firefox. It was at this for about an hour and I knew there was a problem so chose to end process in task manager. Since then I haven't been able to open Firefox: "Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system". I uninstalled Firefox using Revo Uninstaller and deleted all leftover files, restarted my computer and installed Firefox, but the problem still remains. I tried looking through previous questions and noticed I do no have a profile folder which may be needed to delete a lock file.... Any help much appreciated! thanks

All Replies (4)

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The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. Note: This will cause you to lose any Extensions, Open websites, and some Preferences.

To Reset Firefox do the following:

  1. Go to Firefox > Help > Troubleshooting Information.
  2. Click the "Reset Firefox" button.
  3. Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
  4. Firefox will open with all factory defaults applied.


Further information can be found in the Refresh Firefox - reset add-ons and settings article.

Did this fix your problems? Please report back to us!

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I had this problem yesterday, actually. You can solve it, but you will lose all firefox data you didn't back up. Then again, because you already tried uninstalling and reinstalling, I assume this isn't an issue.

Assuming you've installed windows on the C drive:

Go to C://Users/yourname/AppData

If you cant find it, go to your display settings (I hope I translated this correct; I use the Dutch version of Windows) and make sure that hidden files and filders are not being... well, hidden. Shocking plottwist, I know.

If all goes well, you should now see three folders named Local, Localrow and Roaming.

Now go to Roaming > Mozilla > Firefox and delete everything thats in there. Now you have an empty FireFox folder, which will force Firefox to start up as if it was never installed before.

Done! :)

P.S. Now that you have a fresh new install, save yourself a lot of future pain and install Xmarks for your bookmarks and LastPass for your passwords. These add-ons will keep your data safely on their servers, where it is yours to backup and download anywhere in the world.

Also, if you have about three milion add-ons and personas/themes and you don't want to hunt hem down again everytime you reïnstall Windows or buy a new system, get FEBE to save a copy of them for you. And if you really want to backup like a pro, install DropBox (not an addon) and tell FEBE to store its files there, so you can still retrieve them if your house happens to burn down.

Xmarks, LastPass and FEBE: the holy trinity of Firefox backups :P

Modified by Thalia0123

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Check whether you still have a profiles.ini file left in the "%App%\Mozilla\Firefox" folder.

If you still have a profiles.ini file, but the profile folder is gone then delete the profiles.ini file to force Firefox to create a new default profile.

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Thank you very much you explained it perfectly and fixed my error! Have a great day! :)