Search Support

Beware of phishing attacks: Mozilla will never ask you to call a number or visit a non-Mozilla website. Please ignore such requests.

Learn More

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.

  • 2 replies
  • 192 have this problem
  • 4820 views
  • Last reply by Moses

more options

I attempt to open firefox and despite firefox NOT being open I get the following 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."

Once restarted it works fine but does re-occure

All Replies (2)

more options

Press CTRL+ALT+DEL, open the task manager and click on "Processes". If Firefox is still running you can close it from there. Not a complete fix but it spares you the reboot.

more options

Hi,

This is a currently reported bug and it's being worked on. Mozilla will release an update to 29 tomorrow to fix some of the most commonly reported issues in the forum. You can either wait for the update or you can try the workarounds.


One workaround is to set network.seer.enabled to false

  • Navigate to about:config in your Address Bar
  • Press the "I'll be careful, I promise!" button to proceed
  • search for network.seer.enabled
  • Set that to false by right clicking and selecting Toggle