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!

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

When I try to open Firefox 3.6 (Mac) by clicking on the icon, I get this message: "Close Firefox: A copy of Firefox is already open. Only one copy of Firefox can be open at a time." I've removed older versions and restarted, but still get this message. Wh

more options

I've just downloaded Firefox 3.6 (Mac). When I attempt to open, this message pops up: "Close Firefox: A copy of Firefox is already open. Only one copy of Firefox can be open at a time." I've removed older versions and restarted, but still get this message. What's going on?

This happened

Every time Firefox opened

after I downloaded the latest version.

User Agent

Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_3; en-us) AppleWebKit/531.22.7 (KHTML, like Gecko) Version/4.0.5 Safari/531.22.7

I've just downloaded Firefox 3.6 (Mac). When I attempt to open, this message pops up: "Close Firefox: A copy of Firefox is already open. Only one copy of Firefox can be open at a time." I've removed older versions and restarted, but still get this message. What's going on? == This happened == Every time Firefox opened == after I downloaded the latest version. == == User Agent == Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_3; en-us) AppleWebKit/531.22.7 (KHTML, like Gecko) Version/4.0.5 Safari/531.22.7

All Replies (1)

more options

You might find your solution in this article.