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Get error msg: A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

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Grand Master

Get error msg: A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

Get the following msg. when I try to open Firefox: " Close Firefox. A copy of Firefox is already open. Only one copy of Firefox can be open at a time." No other copy is installed or running.

This happened

Every time Firefox opened

== After I reloaded a new copy of OS X. Previous system folder was archived.

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20 REPLIES
Shooting Star

Re: Get error msg: A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

Hello Vernon.

That may have happened because Firefox hanged or is taking to long to close. Access your task manager and terminate Firefox's application. That will loose you no data and will allow you to run Firefox again.

It's probable that it's just taking a bit longer to close, though, so waiting a bit will probably fix the issue (like a few seconds, so this for future reference).

Site Moderator

Re: Get error msg: A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

Grand Master

Re: Get error msg: A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

I have the same problem. Running OSX 10.6.3

I have restarted, started in safe mode, fixed permissions, reinstalled FireFox. All the standard stuff.

FireFox does not show in System Monitor.

This is not a problem of FireFox taking too long to close - unless you consider three days and several restarts too long.

Clearly the answer was proposed by someone without Mac OSX experience.

...rmk
Grand Master

Re: Get error msg: A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

I have the same problem, I am able to find it still running by using ps in terminal but even a kill -9 wont stop the process. A reboot will fix it but obviously thats not a very good solution.


bash# ps -ef | grep firefox

 501  1885   116   0   0:00.00 ??         0:00.00 (firefox-bin)
 501  1953  1946   0   0:00.00 ttys000    0:00.00 grep firefox
New User

Re: Get error msg: A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

Dear Vernon - this is not a matter of waiting. I believe you are on a PC. On my Mac running the current OSX and the current FF, we will get a message saying that a copy of FF is already open and that 2 copies cannot be open at the same time. It does not appear in the Mac Activty Monitor (windose task manager) and so cannot be force quit - it requires restarting the system. Essentially FF makes using the computer impossible.

Shooting Star

Re: Get error msg: A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

Can you please try it in a new (temporary) Firefox profile and see if the issue is still present? See this article to know how to create a new Firefox profile. Please report back the results.

Site Moderator

Re: Get error msg: A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

New User

Re: Get error msg: A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

Are you sure you tried killing the right process id? “ps -ef” is a Linux/SVR4-ism and the first column is the parent process id, not the process id. On OS X and other BSD Unix system, “ps -ax” is the way to go and gives the process id in the first column.

New User

Re: Get error msg: A copy of Firefox is already open. Only one copy of Firefox can be open at a time.

I was able to use 'kill -9 PID' (PID - Process ID - first column if you use the 'top' command in terminal) to kill the firefox-bin process and then restart firefox successfully.