Comments on: Fix for “Close Firefox: A copy of Firefox is already open.” error

By: dg

dg — Tue, 29 Jan 2013 03:15:28 +0000

Thanks for this, FF was missing from activity monitor; this fixed the problem

By: Luis Franco

Luis Franco — Tue, 22 Jan 2013 17:53:34 +0000

Thanks a lot, this fix solved my problem

By: Stephen King

Stephen King — Fri, 18 Jan 2013 22:13:53 +0000

See … this is why I love the internet. 1 minute from having the error, I found your instructions, corrected the issue and am running Firefox again.

THANKS!!!

By: Jana

Jana — Wed, 02 Jan 2013 20:39:24 +0000

Thanks for this one!

By: Brett

Brett — Thu, 22 Nov 2012 01:24:53 +0000

I love you!

Now if only I hadn’t already deleted FF and downloaded a newer version, I wouldn’t have to be making sure all my add-ons still work etc.

By: hallelujah

hallelujah — Tue, 02 Oct 2012 01:53:48 +0000

Great fix after a 7 hour nightmare…brilliant solution for 10.7.5

By: Foggy

Foggy — Mon, 30 Jul 2012 12:56:08 +0000

I just deleted the Firefox App support folder. 10.7.4
Worked fine for me.

By: schaulinsan

schaulinsan — Tue, 24 Jul 2012 12:30:21 +0000

nice solution description, worked perfectly and saved me a restart . tnx!

By: Pricey

Pricey — Fri, 15 Jun 2012 09:26:49 +0000

If you read the description then you will find that ‘alaklrac.default’ is his own random file name, by the looks of things then ‘ajain2$.default’ is your random file name.

So in which case you would use the following commands :-

cd ~/Library/Application\ Support/Firefox/Profiles/

cd ajain2$.default

rm -rf .parentlock

cd ~/Library/Application\ Support/Firefox/Profiles/*.default

and to those who used the Activity monitor to stop firefox, then wouldn’t a simple reboot stop the error appearing anyway?

After using this command I have found that no Mac (I work in a school) has had the same problem again.

By: Adi

Adi — Fri, 17 Feb 2012 23:59:33 +0000

xec rm {} \;
brandw10:~ ajain2$ cd ~/Library/Application\ Support/Firefox/Profiles/
brandw10:Profiles ajain2$ ls
brandw10:Profiles ajain2$ cd alaklrac.default
-bash: cd: alaklrac.default: No such file or directory

NOT working.. what would i do …plzzz help.. tried everything….

By: Jon

Jon — Thu, 23 Jun 2011 23:43:41 +0000

BRilliant, worked first time – many thanks

By: Jörg

Jörg — Fri, 10 Jun 2011 18:29:42 +0000

Thanks. For my installation the
~/Library/Application\ Support/Firefox/Profiles/*.default
location is
~/Library/Application\ Support/Firefox/*.default

Here my suggestion for a one line command

rm -i ~/Library/Application\ Support/Firefox/*.default/.parentlock

By: Phil

Phil — Wed, 01 Jun 2011 14:32:26 +0000

EXCELLENT, this worked. THanks

By: Haziq

Haziq — Sun, 15 May 2011 01:54:27 +0000

You deserve a cookie.

I am so happy that Im crying.

DDDDDDDD((((((((((((((

By: Marcus Lisle

Marcus Lisle — Wed, 04 May 2011 04:35:49 +0000

Thank you very much, lleaning!

You saved me much time and aggravation. The Activity Monitor app was an easy way to fix the problem.