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Firefox still running after I close it

  • 15 replies
  • 277 have this problem
  • Last reply by rabii

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Prior to the last couple of weeks, once in awhile after closing Firefox and attempting to relaunch it, I would get an error message that it was still running and I had to close it before I could relaunch it. The last 2 weeks this happens just about every other time. I'd like to figure out if I have a setting that's bad or if recent Firefox updates caused this to increase or what. If anyone can help, I'd be greatful.


All Replies (15)

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Do a clean reintall or a reset:

Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:

Note: You might want to print these steps or view them in another browser.

  1. Download the latest Desktop version of Firefox from and save the setup file to your computer.
  2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
  3. Delete the Firefox installation folder, which is located in one of these locations, by default:
    • Windows:
      • C:\Program Files\Mozilla Firefox
      • C:\Program Files (x86)\Mozilla Firefox
    • Mac: Delete Firefox from the Applications folder.
    • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
  4. Now, go ahead and reinstall Firefox:
    1. Double-click the downloaded installation file and go through the steps of the installation wizard.
    2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

More information about reinstalling Firefox can be found here.

WARNING: Do not run Firefox's uninstaller or use a third party remover as part of this process, because that could permanently delete your Firefox data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. These cannot be recovered unless they have been backed up to an external device!

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 and some Preferences.

  • Open websites will not be saved in Firefox versions lower than 25.

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!

Thank you.

Modified by Diego Victor

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I've done that now and I'll try it for awhile and see what happens. Thanks for the suggestion.

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This didn't work. The very first time I went to relaunch Firefox I got the same error message.

"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."

In Task Manager, there are no browsers open, so I have no way to close Firefox (that I know of) and consequently have to reboot the computer every time.

More suggestions/cures?

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I followed this article and deleted the parentlock file. Went back into FF a few times and played around and exited and after the fourth time, it wouldn't launch. Went into task manager and closed the FF program that was still running. Went back into the start menu and brought up the FF defaults menu and the parentlock file was back. I've deleted it again, but it's obviously going to come back.

So I guess the question is, what's causing this file to rebuild itself and are there any other cures?

Thanks for your time and help.

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Firefox rebulding it, here there are more ideas:

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I read the article above and another one posted in that. One thing that it lead me to were my add-ons. I'd downloaded a coupon program from Mozilla a week or so ago that has been a pain to use and then get rid of. When I went to the add-on page and disabled/deleted that, things seemed to have improved. Not sure if it's fixed yet, but I'm running ok for now. If it continues, I'll post again.

Thanks for the help.

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This has been a near-constant problem for me ever since upgrading from v. 28 to v. 29. Almost every time I shut down, Firefox fails to close and has to be manually closed from the task manager.

I'm switching to the Google Chrome browser until you get this sorted out--and maybe permanently.

Update (Aug. 4, 2014): Updating v. 30 cleared up the problem with no further action from me (no clean reinstallation, no inactivation of add-ons, etc.). For me, this was entirely a result of changes which were embodied in the upgrade from v.28 to v.29 and which were, apparently, corrected or at least altered in v.30.

Modified by lpj97007

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From what I have been reading from other posts on this forum, the issue may be caused by the clear history settings.

Press the <Alt> or <F10> key to bring up the tool bar. Followed by;

Windows; Tools > Options Linux; Edit > Preferences Mac; application name > Preferences

Then Privacy.

The button next to History, select Use Custom Settings.

At the bottom of the page, turn on Clear History When Firefox Closes. At the far right, press the Settings button. Turn on ONLY Cache and Form And Search History leaving the others off.

This is not a cure but will make it easier if Firefox locks up. {web link}

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I am sorry but a re-install is a very big hammer. The right solution is to have a patch or an update that fixes the problem. Otherwise doing a full re-install and losing all your addons just to try an idea is not acceptable.

If this was a one time deal and we knew it will fully fix all the problems that would be something but as others said it does not seem to work. It is a lot simpler and less risky to go in task manager and shut it down.

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The problem was never fixed until recently when Mozilla brought out a new update. (A week ago?) ever since then, I've had zero problems closing and re-opening Firefox...

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I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution more easily.

Thank you for contacting Mozilla Support.

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I appreciate your response, but I'm not going to close this just yet since, #1 people need to see that the new version may have cured the issue and #2, I don't believe enough time and use has passed to warrant closing this since the potential is certainly there for it to start up again--it didn't start with a new version back in February--it simply popped up for whatever reason.

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I just started having this problem, even though I am running the latest version, Firefox 31. After reading a few of the suggested solutions, I thought maybe one of my add-ons was causing a problem, so I tried restarting Firefox in safe mode, with all add-ons disabled. This worked, not only for that one time, but also after restarting normally. I haven't had a problem with it since. I'm assuming it forced a reset of the add-ons I have installed. Perhaps this is an alternative to a clean reinstall where you lose all of your add-ons until you reinstall them. I hope this helps.

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One alternative to a re-install and/or removal of profile is the following:

1) Go and create a new user on Windows. 2) Log into the newly created account. 3) Bring up firefox.

This should give you a new profile with only the default settings. If this fixes your problem then you at least know that going back to default will be a viable fix. If not then there is no point in going through that path.

Hope it helped.

Modified by rabii