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

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New User

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

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

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4 REPLIES
New User

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

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!

New User

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

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! Smiley Happy

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 Smiley Tongue

Site Moderator

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

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.

New User

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

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