Where did you install Firefox from? Help Mozilla uncover 3rd party websites that offer problematic Firefox installation by taking part in our campaign. There will be swag, and you'll be featured in our blog if you manage to report at least 10 valid reports!

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

Firefox will not open - it says it has a copy open already - and it does not. This happened after I tried to update to new firefox.

  • 2 replies
  • 2 have this problem
  • 5 views
  • Last reply by cor-el

more options

I attempted to upload the new version of Firefox. When I did this - I could not open Firefox at all - a box pops up telling me to 'Close Firefox - a copy of firefox is already open - Only one copy of Firefox can be open at a time.

I tried to remove Firefox completely form the computer and reinstall - and I get the same message.

I am using a macbook prop with Lion operating system

I attempted to upload the new version of Firefox. When I did this - I could not open Firefox at all - a box pops up telling me to '''Close Firefox - a copy of firefox is already open - Only one copy of Firefox can be open at a time.'' I tried to remove Firefox completely form the computer and reinstall - and I get the same message. I am using a macbook prop with Lion operating system

All Replies (2)

more options

Must be the "hang at exit" problem. You already know how to do Step1; now just determine which Add-on (Extension or Plugin) is causing the problem.

  1. Stop the Firefox process:
  2. Why Firefox may hang:
  3. Use Firefox Safe Mode to find a problem with an Extension or Plugin:


If this reply solves your problem, please click "Solved It" next to this reply when signed-in to the forum.

more options