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.

Avatar for Username

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

This thread was archived. Please ask a new question if you need help.

Unable to open a new window you must first close exsisting firefox process or restart your system. There is no firefox process running why should I receive this error msg?

  • 1 reply
  • 15 have this problem
  • 4 views
  • Last reply by TXGuy

AnonymousUser
AnonymousUser
more options

I closed a Firefox process. Then clicked the FF icon to restart my browser. I received an error message. " Firefox is already running, but not responding. To open a new window you must first close existing Firefox process, or restart your system. However there is no Firefox process running to begin with. I checked the task manager.

This happened

Every time Firefox opened

I closed a Firefox process. Then clicked the FF icon to restart my browser. I received an error message. " Firefox is already running, but not responding. To open a new window you must first close existing Firefox process, or restart your system. However there is no Firefox process running to begin with. I checked the task manager. == This happened == Every time Firefox opened

All Replies (1)

TXGuy
TXGuy
more options

It takes Firefox 5-15 seconds to completely close and for the OS to release the processes; it may take longer if you have a Flash animation/video running in one of the tabs. If not waiting long enough is not the problem, you can try the following to determine if an Extension or Plugin might be causing Firefox to hang at exit.

Kill Application In Task Manager, does firefox.exe show in the Processes tab? See: Kill Application

Causes and solutions for Firefox hanging at exit: Firefox hangs or is not responding - How to fix Firefox hangs at exit "Firefox is already running but is not responding" error - How to fix

Safe Mode You may need to use Diagnose Firefox issues using Troubleshoot Mode (click on "Safe Mode" and read) to localize the problem. Firefox Safe Mode is a diagnostic mode that disables Extensions and some other features of Firefox. If you are using a theme, switch to the DEFAULT theme: Tools > Add-ons > Themes before starting Safe Mode. When entering Safe Mode, do not check any items on the entry window, just click "Continue in Safe Mode". Test to see if the problem you are experiencing is corrected.

See: Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems Troubleshoot and diagnose Firefox problems

If the problem does not occur in Safe-mode then disable all of your Extensions and Plug-ins and then try to find which is causing it by enabling one at a time until the problem reappears. You MUST close and restart Firefox after EACH change via File > Restart Firefox (on Mac: Firefox > Quit). You can use "Disable all add-ons" on the Safe mode start window.