Join the AMA (Ask Me Anything) with the Firefox leadership team to celebrate Firefox 20th anniversary and discuss Firefox’s future on Mozilla Connect. Mark your calendar on Thursday, November 14, 18:00 - 20:00 UTC!

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

I have tried uninstalling and reinstalling Firefox several times. Every time I try to open Firefox I get an error message saying "Close Firefox"," A copy of Firefox is already open. Only one copy of Firefox can be open at a time."

  • 2 replies
  • 12 have this problem
  • 9 views
  • Last reply by dougdwr

more options

I uninstall Firefox, then reinstall Firefox, try to open Firefox, and get an error message in a popup box saying,

"Close Firefox"

"A copy of Firefox is already open. Only one copy of Firefox can be open at a time."

I uninstall Firefox, then reinstall Firefox, try to open Firefox, and get an error message in a popup box saying, "Close Firefox" "A copy of Firefox is already open. Only one copy of Firefox can be open at a time."

Chosen solution

Create a new profile as a test to check if your current profile is causing the problems.

See "Basic Troubleshooting: Make a new profile":

If that new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files.

See:

Read this answer in context 👍 3

All Replies (2)

more options

Chosen Solution

Create a new profile as a test to check if your current profile is causing the problems.

See "Basic Troubleshooting: Make a new profile":

If that new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files.

See:

more options

That solved the problem. Thank you very much!!!!