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.

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

Error message that old firefox is running when starting firefox

  • 1 reply
  • 0 have this problem
  • 4 views
  • Last reply by cor-el

more options

Starting today (Apr 30), when trying to open firefox the following message appears:

"Firefox is running, but not responding. The old Firefox process must be closed to open a new window." My options are to close firefox or cancel.

When selecting close firefox, the message will reappear with the same options. I am unable to run.

Steps I have taken: Uninstall Firefox Download latest Install

Message still appears

Starting today (Apr 30), when trying to open firefox the following message appears: "Firefox is running, but not responding. The old Firefox process must be closed to open a new window." My options are to close firefox or cancel. When selecting close firefox, the message will reappear with the same options. I am unable to run. Steps I have taken: Uninstall Firefox Download latest Install Message still appears

All Replies (1)

more options