How to fix “Firefox is already running” error

Strangely enough my computer froze yesterday when i was browsing in Firefox – had to manually reset. Today when i started the browser it knew what happened and asked me if i wanted to restore the session (no error..).

However, i got the error described in this post some time ago when i tried to launch Firefox. You know when you launch something and it sometimes takes (longer than expected) time to actually start (although you can see the process in Task Manager) ? Dunno why that happens, but that time when i launched Firefox it was the same. Didn’t know what happened in the beginning, so i launched it again. That’s when i got the error.

This happens to me when I goof the sharing of firefox bookmarks via a share drive and common profile file. I dual boot an XP and FC5 machine with my users have their mozilla profiles on a share. If I use the wrong filename (misread letter l for the number 1 for instance) I get the error message.

Just got a copy of Ubuntu in the mail, for those who want to try it go > https://shipit.ubuntu.com/

Thanks for the tips!

I get that firefox message many days a week. I consider it a major bug: not only should ffox fix its own corruption, but it should not be able to get into (or even near) that state.

Obviously the web browser is going to be the main program we run on our computers. Yet if I said I wanted my IM tool, my word processor, my web page viewer, my shell, and my MUA to be all in one big process with one shared memory space, unable to be run simultaneously on multiple boxes (with shared home dir), people would accuse me of throwing out 20 years of OS development.

The ffox folks probably say they’ve “optimized for the common case” or they’re “making things convenient for their users by locking all the profile settings to one process”. I don’t get it, though. I can share my volatile imap inbox across multiple processes (on multiple boxes), but my barely-changing set of trusted SSL certs is too difficult to share between two long-running web browser processes?

We actually wrote a custom script for our Linux desktop users that would check for and remove the lock files *every time* they started Firefox. A quick and dirty workaround, no doubt, but having ten end-users complaining about this problem multiple times per week got to be unbearable.

I will say that Firefox 2.0 seems to be a bit better about this problem though.

You can receive that message if your operating system allows more than one user connected at the same time (Windows 2003 for example).

If you’re logged in on the PC, using Firefox and you connect from another computer to your computer and log in using the same account, when trying to start Firefox you’ll get that message because the lock files exist but the Firefox in the remote connection can not access the Firefox from the other session.

I’ve actually reported this “bug” a few months ago to the team and i got stupid answers, the conclusion was that they won’t bother to fix this. (didn’t argue further, it was pointless)

They also mentioned a possible workaround, here’s the bug listing and the workaround:

https://bugzilla.mozilla.org/show_bug.cgi?id=348721

Firefox was great at first however I feel personal that browser wise Firefox is slipping and others have caught up. I’ve gone back to IE and the new browser is great, you’ve pointed out one problem with firefox but I feel there is a lot more wrong.

First of all: IE is NO alternative for dual boot systems

Second:
if you follow this instructions, http://www.geektimelinux.com/index.php?q=node/view/362 you might experience the problems described above.
We could fix the problem with plain symbolic link instead of regular path.

Works great.

I only get that problem because I like to run multiple Firefox profiles (at once or not) and I had to modify the shortcuts to look something like this:

D:\Program Files\Mozilla Firefox\firefox.exe” -p profilename -no-remote

This problem pops up when Firefox is running and an external application tries to open a new Firefox window (for example, from help file, or pdf file or whatever). I still haven’t found a way to solve this

Andrew,

YOU WROTE: “This problem pops up when Firefox is running and an external application tries to open a new Firefox window (for example, from help file, or pdf file or whatever). I still haven’t found a way to solve this.”

SOLUTION: Right-click on “My Computer”, then click “Properties” > “Advanced” (tab) > “Environment Variables”. Under “System variables”, delete the “MOZ_NO_REMOTE” variable.

I had the same problem you described, and this solution worked for me. Hopefully it will work for you also!

Thanks a lot, it worked !!

I 8use mozilla fire fox. i keep getting error ads need to be loaded from adcode. what is the problem and how can i fix it. when visiting a website it keeps saying windows cannot find null.

Been wanting to use firefox for a weeknow and it didnt work. renaming the profile sure did the trick. Thank you.

Daniel: I have the same problem Andrew has, but I don’t have a MOZ_NO_REMOTE environment variable set anywhere. Like Andrew, I’m using the -no-remote command-line switch, not an environment variable, in order to run multiple instances.

This problem occurs even if I have only one instance running, so long as that instance is not using my default profile.

My GUESS is that when you click on a link, it wants to activate your default profile. If I only have one copy of firefox running, and it’s using my default profile, then clicking on the link will work. If I have two copies running, then clicking on the link won’t work. If I have only one copy running, but it’s NOT using my default profile, then clicking on the link won’t work. Sometimes it’s annoying and cumbersome to get the URL to copy-and-paste it: e.g., if you get an email with a link in it.

Hi Judy,

If you’re using windows, you can try this program:
http://www.topdrawerdownloads.com/download/104402

Otherwise, if you’re using Linux, at a command prompt, type in:
lsof ~/.mozilla/firefox/[Profile name]/.parentlock
If nothing shows up there, you’ve got a much bigger problem. You’re going to have to umount the file system or mount it read only mode and run fsck (file system check) on it.

If mozilla is displaying this because you are on a network with a roaming profile which happens alot you just go to C:\Documents and Settings\%Username%\Application Data\Mozilla\Firefox and modify the profiles configuration settings to another path, or remove completly and save, this should keep this from happening.

Thanks Ron

I have windows xp media center edition OS.

Firefox says firefox is already running please close it to open a new.. blah blah blah you know the deal.

Already tried going into task manager, not there so i cant end firefox.exe.

I’ve reinstalled, i’ve restarted.

Anything else i should try???

Hey all – to fix this problem I wrote a batch file (If you have windows folow this:)

Open Notepad.
Paste in the following :

———–Copy Below Here————-

@echo off

setlocal
set exeName=%~1
if “%~1″==”" set exeName=”firefox”
if “%exeName%”==”" echo Processing aborted&pause&goto :EOF
call :GETNAME “%exeName%”

set found=

for /f “tokens=*” %%a in (‘tasklist ^| findstr /i “%fileName%”‘) do set found=Y

if “%found%”==”Y” call :endfirefox
taskkill /f /im “cmd.exe”

:GETNAME
@cls
set fileName=%~nx1
goto :EOF

:endfirefox
@echo off
@cls
taskkill /f /im “firefox.exe”
“C:\Program Files\Mozilla Firefox\firefox.exe”
taskkill /f /im “cmd.exe”
exit

———–End above here————-

Save as killfirefox.bat (it’s important it saves as a .bat and not a .txt).

Place it on your desktop – if you get that error message simply run the batch file, and it’ll fix it AND start your browser for you.

Nice

Had the same problem on FF3 on Vista.
Ran:
firefox.exe -profilemanager
Selected “Create New”
Pointed it at my old profile directory, select Next. Old settings rebuilt and all my settings came back.

I’m late on this thread but I am trying to solve this problem, and using the advice in this thread. Wish me luck.

I’d like to link the list of add ons that are known to cause problems – I wonder if IE Tab was giving me trouble. I can’t install IE View Lite because I’m in the latest FF version (a Beta) because I needed a different add on that was only for the Beta (SIGH)

In case this helps anyone:
http://kb.mozillazine.org/Problematic_extensions

I dont know if anybody can help me but, I’ve been using firefox and ever since i upgraded to 3.05 i cannot get a connection to the internet and its been doing this for about a week

I had the problem (frequently) with Vista.

Rebooting always fixed it, but I’d had enough, and wanted to fix it without rebooting.

I found the parent.lock file in C:\Users\\AppData\Roaming\Mozilla\Firefox\Profiles\, and tried to delete it. Windows prevents it, saying that it’s in use (even though Firefox is not in the task manager).

So I opened up a DOS shell, cd’d to C:\Program Files\Mozilla Firefox\ and ran “firefox.exe -profilemanager”.

I created a new profile, and used the browser (in the wizard) to make it point to the old profile. No dice – it still thinks the “parent.lock” is in use.

This worked:

– I used Explorer to copy the profile folder, within the Profiles folder. Windows doesn’t copy the “parent.lock”, and another file, because they are “in use”. Rename the new folder to “new.default”
- Run “firefox.exe -profilemanager”
- rename the old profile to “profile.save”
- create a new profile, call it “default”
- When the wizard asks for a profile folder, browse to the copied folder, ie. “new.default”
- Run Firefox!

I had the same problem, but had been running my main profile using the -no-remote switch. To be able to run links from external programs (e.g., double clicking a link in an email client), the -no-remote switch has to be removed. Mozilla’s documentation states that it should never be run for the default profile (which it would seem also applies to whatever profile you use most of the time). (This documentation was mentioned in the original article above and may be found here: http://kb.mozillazine.org/Profile_in_use)

For the record, I removed the switch and everything works like a charm now.

I fixed firefox by uninstalling zone alarm and using comodo firewall

I found that to bypass the error, not fix was to create a .bat file. It’s this exactly:

taskkill /im firefox.exe
START firefox.exe

Since you usually close firefox manually you don’t need to worry about accidentally pressing the button. This just prevents the Firefox is still running by beating it to the finish line. First it ends the FireFox process, and then 2 Seconds later it starts firefox up.

I have 2 accounts on my PC. When I go to the other account I close Firefox on the one I’m leaving. The problem is when I go to the other account and open Firefox and try to update my Add-ons I keep getting the error message that, “The update could not be installed. Please make sure that there are no other copies of Firefox running on your computer, and than restart Firefox to try again.”

I get the same error message when I try to update my Add-ons on my other account, too.
This is a fairly new problem.

Thank you, Patricia Rodela