Error: "firefox is already running". Won't start until I stop process on task mgr.

I cannot start firefox. Error message tells me that it is already running.
It is not running, but shows in task manager processes. If I end the process, I can start Firefox.

-> press '''CTRL''' + '''SHIFT''' + '''ESC''' to Open Task Manager -> Processes tab -> right-click '''firefox.exe''' and click '''End Process Tree''' -> close Task Manager
Troubleshooting extensions and themes
* https://support.mozilla.com/en-US/kb/Troubleshooting%20extensions%20and%20themes
Troubleshooting plugins
* https://support.mozilla.com/en-US/kb/Troubleshooting%20plugins
Check and tell if its working.

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Doesn't start when starting as administrator. Error Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system.

Update firefox, it asked me to update flash, I tried to update flash but it said I had to close firefox. A box came up and said the Flash install would continue when I closed firefox. I closed all firefox windows and no update of flash occurred. I tried relaunching firefox but got the "Doesn't start when starting as administrator. Error Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system." message. I rebooted the system, no improvement. I tried to run firefox as administrator and got the same message. Either I find a fix or I won't be able to use firefox and will have to go back to ie.

-> press '''CTRL''' + '''SHIFT''' + '''ESC''' to Open Task Manager -> Processes tab -> right-click '''firefox.exe''' and click '''End Process Tree''' -> close Task Manager
Troubleshooting extensions and themes
* https://support.mozilla.com/en-US/kb/Troubleshooting%20extensions%20and%20themes
Troubleshooting plugins
* https://support.mozilla.com/en-US/kb/Troubleshooting%20plugins
Check and tell if its working.

Frequently get error "Firefox is already running" when using desktop shortcuts to web sites

I love Firefox and don't want to use another browser. I frequently get the error "Firefox is already running". I even created a batch file to kill the process so I can re-launch it. There has to be a real solution.
The key to my issue is... I use shortcuts to web sites from my desktop. This is what seems to trigger the error (but not every time). Please don't tell me to stop using shortcuts; that isn't a solution.
I am using Windows 8.1 64 bit
Firefox 32.0.1 (had this same problem with all prior versions too)
Any help is appreciated!

Separate issue;
Your System Details shows;
Installed Plug-ins
Shockwave Flash 15.0 r0
Shockwave Flash 14.0 r0
Having more than one version of a program may cause issues.
Flash is notorious for not cleaning out the older version as part of an update.
Grab the uninstaller from here:
'''[http://helpx.adobe.com/flash-player/kb/uninstall-flash-player-windows.html Uninstall Flash Player | Windows]'''
'''[http://helpx.adobe.com/flash-player/kb/uninstall-flash-player-mac-os.html Uninstall Flash Player | Mac]'''
Then reinstall the latest version.
Shockwave Flash '''v15.0.0.152 http://get.adobe.com/flashplayer/'''
fixed last link as it incorrectly was for shockwave player instead of the proper flash player. If it has shockwave in a adobe link then that is not Flash.

FFox 3.6.8. Repeated problem. I close it, then hours later try to relaunch it, and it says it's still running. So I have to End Process in Task Mgr. Also, plug-container keeps running and takes LOTS of memory. Ergo, 3.6.8 is a step backward.

FFox 3.6.8. Repeated problem. I close it, then hours later try to relaunch it, and it says it's still running. So I have to End Process in Task Mgr. Also, plug-container keeps running and takes LOTS of memory. Ergo, 3.6.8 is a step backward. I wish I hadn't upgraded. What can be done?
== This happened ==
Every time Firefox opened
== I upgraded to 3.6.8. Not before.

See http://kb.mozillazine.org/Firefox_hangs and [[Firefox hangs]] (Hang at exit)

If Firefox is set as the default browser, and any application attempts to open a new window, this fails and I get the error "Firefox is already running..."

Here is what I am running:
Microsoft Windows 7, Service Pack 1, Fully updated to 4/10/2012
Fresh Install of Firefox 11. No add-ons enabled as a result of troubleshooting.
I am a user with administrator rights
UAS is disabled.
To begin, this has been going on Since Firefox 10 or so. A few months now.
I am able to open Firefox. My add-ons worked (ABP, Flashblock, ABP Element Hiding Helper, IETAB2, Downthemall, Greasemonkey, 4chan extension) had no problems. Firefox is set and has been set for the last two years as my default web browser.
However Since approximately Firefox 10 or so, maybe before that, If I have a Firefox session open, and any other application attempts to open a session in a new window, I get the Firefox is already running, but not responding error."
I attempted to follow troubleshooting advice already posted (look for parent.lock files left behind [none present], multiple sessionstore.js files [none present], create a new user profile, attempted to clear out the "read-only" permission in windows 7, however as soon as it is cleared, the read only permission returns.)
As a last resort, I deleted the Firefox folder, the %APPDATA%/Mozilla directory in its entirety, then utilized CCleaner to remove any and all references to Firefox in the windows registry, then did a full re-install, no extensions installed right now.
I checked preferences and have the option "open new windows in a new tab" checked off. The problem persists regardless if this option is checked on or off. This problem persists in or out of safe mode, even with the brand new install.
Test Cases:
All cases:
Firefox is selected as the default browser for windows 7
Case 1: Open a firefox session. Utilize any other program that attempts to open a link to their website in a new browser window or new browser session. Experience "Firefox is already running" error
Case 2: Open a firefox session. Right click on Firefox on the task bar. Select "open in new window". Experience "Firefox is already running" error
Case 3: Open a firefox session. Select the Firefox Menu > New tab > New Window. A new window will actually open.
This is the only method of opening a new window in the same browser session or profile that actually works on my system. Attempting to open a browser session from the task bar "open new window dialog" or opening a new window while a current window/session is running will not open firefox in a new window or a new tab in the current session. The "Firefox is already running, but is not responding" error will occur every time.

Cor-el's suggestion resolved my problem. Apparently the MOZ_NO_REMOTE variable was set to 1 on my system variables. I never made it, and really have no idea how it got there, but deleting this variable and restarting firefox has resolved the issue. Thanks Cor-el!
Marking case: Solved
Solution: Verify the MOZ_NO_REMOTE variable is NOT set to 1. This can be achieved by simply deleting this variable.

My computer thinks firefox is running and will not open browser window,error = firefox is already running, you need to terminate the process or restart computer. restart has no effect. what file would make the computer think firefox is running?

Reinstalling does not help. Computer locked up for unkown reason and this has happened ever since when i try to start firefox.
Is there a file I can delete or kill that will terminate this process?

See:
* http://kb.mozillazine.org/Profile_in_use
* https://support.mozilla.com/kb/Firefox+is+already+running+but+is+not+responding
Create a new profile as a test to check if your current profile is causing the problems.
See "Basic Troubleshooting: Make a new profile":
*https://support.mozilla.com/kb/Basic+Troubleshooting#w_8-make-a-new-profile
There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems.
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:
*http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

F/fox won't run. Prev. ok - upgrade in ver 7 caused problem - reinstalled now won't run at all. last try with ver 8. Error : "Firefox is already running, .. not responding .. close .. or restart .. system." Neither helps.

'''bold text'''The problems started when a routine browser update resulted in a number of sites not loading and firefox merely 'waiting' interminably for the response. But no error messages. Many but not all sites affected. I disabled add-ons and I think I tried to run in safe mode (my own - mental -memory is slightly damaged) I am no expert but nothing I tried seemed seemed to work so I uninstalled and re-installed. I got the problem described above so I uninstalled using another un-installer (Advanced System Care). Problem remains and I cannot find any process 'obviously' connected with firefox using Task Manager. Can't get troubleshooting info 'cause I can't run FF

Does the ext directory have the php_oci8.dll? In the original steps the PHP dir is renamed. In the given php.in the extension_dir looks like it has been updated correctly. Since PHP distributes php_oci8.dll by default I reckon there would be a very good chance that the problem was somewhere else. Since this is an old thread I don't think we'll get much value from speculation.
-- cj

How do I stop this error "Firefox is already running, but is not responding"

Hello,
I got this issue where I’m logged into more then on computer at a time. If I have Firefox running on one computer I’m prevented from running Firefox on anther computer. This because my user account has its home directory mounted across all the computers. It appears that the lock file is preventing from running Firefox on the 2nd computer. What I have been doing is deleting the lock file in my home directory. Then I’m able to start Firefox on the 2nd computer. Is there a better way of doing this? Is there away to disable the use of the lock file?
Now I could just exit out of Firefox on the 1st computer but what if I’m running a web app on the 1st computer. What if you are using a shared admin account to such as root or using a RBAC profile. If user1 is using Firefox after become root or assuming a role, then no other user can use Firefox as root or using that role. That makes it very hard to use Firefox then.
Anyway this is mostly a UNIX/Linux question.

Hello,
I thought I should update this post with the answer.
In order to get around the lock file. You can delete it or use profiles.
If your running Firefox from a UNIX, BSD or Linux based OS. To get to the profile popup window use the -p option.
firefox -p
Which will look like the image below.
https://support.cdn.mozilla.net/media/uploads/images/2013-10-01-11-25-06-18a1cb.png
To get the popup all the time uncheck the "Don't ask at startup"
If you don't have a GUI running then you can do this.
firefox -CreateProfile ''profilename''
firefox -p ''profilename''
I hope this helps someone out.

After Upgrading to FF 7, FF does not close properly. I Receive the error "Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system" after closing FF and Re-Opening

in order to open FF a second time i need to manually close the process. i have disabled all plugings

Hi Pelle,
Why did you delete your profile? Also how? Did you use the profile manager or did you delete from the windows file structure?
It sounds like something during the profile delete has stopped Firefox from starting up. Please see the this article and follow the steps:
Please see this article: [http://kb.mozillazine.org/Profile_in_use]
--Edward

Firefox is already running and not responding does not even show in task manger have to manueley shut down computer,it locks up if i use search bar,use my bookmarks it works ok ,can i save my bookmarks and just take it off and reinstallr

i have been fighting this for a week i have been all over your forums and tried everything that it suggested,just not working ,i have never had any problems with firefox in the past it has been on this computer for at least 4 years help!

Hi there, gwinslo. You have come to the right place.
From what I have been reading from other posts on this forum, the issue may
be caused by the clear history settings.
Press the '''<Alt>''' or '''<F10>''' key to bring up the tool bar. Then '''Tools > Options > Privacy'''.
The button next to '''History''', select '''Use Custom Settings'''.
At the bottom of the page, turn on '''Clear History When Firefox Closes.'''
At the far right, press the '''Settings''' button. Turn on ONLY '''Cache''' and
'''Form And Search History''' leaving the others off.
'''https://support.mozilla.org/questions/997866?esab=a&s=&r=1&as=s''' {web link}
This is not a cure but will make it easier if Firefox locks up.

Firefox is already running but is not responding... I get this error ten times a day or more!

I love Firefox and don't want to use a different browser, but the error "Firefox is already running but is not responding" is driving me crazy. The reason I get this error is because I frequently use http shortcuts from my desktop or click links from within a thunderbird email. I hope someone has a solution other than "just use bookmarks" or "just end the task". This is a legitimate (and major) bug and should be fixed! Thank you.

Hello,
See this help article, maybe help:
*[https://support.mozilla.org/en-US/kb/firefox-already-running-not-responding "Firefox is already running but is not responding" error message - How to fix it]

"Firefox is already running" error while opening a Firefox Document

I am a web developer, so I decided to have different versions of Firefox in order to test my web pages.
Thus I decided to install Firefox 3.6 in "C:\Archivos de programa\Mozilla Firefox\Firefox 3.6", Firefox 4 in "C:\Archivos de programa\Mozilla Firefox\Firefox 4" and Firefox 5 in "C:\Archivos de programa\Mozilla Firefox\Firefox 5".
Moreover, each version has its own profile. In 'profiles.ini' I moved the line 'Default=1' from 'default' profile to 'Firefox 5' profile.
Since then, if Firefox has started, when I try to open a Firefox Document (like .htm or .xml) from a folder, I get "Firefox is already running, but is not responding" error. But the fact is that Firefox is responding correctly. If I write the file's location in Firefox's location bar it works properly.
In the registry, the FirefoxHTML's open command is "C:\Archivos de programa\Mozilla Firefox\Firefox 5\firefox.exe" -requestPending -osint -url "%1". Is it rigth?

I don't have much difficulty with this problem. It's more of an annoyance.
A ''frequent'' annoyance.
What I'll do is log in to a page that requires a secure connection, and when I'm finished, to complete the security, I always close the browser. Then, of course, I start the browser up again.
The problem is, ''Firefox is still shutting down'', and issues this error. Most of the time, I can wait 10 seconds, then start up fine.
'''So my question is,''' why the heck can't the process that detects that Firefox is still running do the waiting for me? Instead of popping up a message, "Firefox is still running", pop up a message, ''"Firefox is cleaning up from the last shut-down, one moment please"'', then start up again.
I hate to mention it, but none of Firefox's competitors have any problem with starting up too soon after a shut-down.

When I attempt to open firefox an error message appears telling me that firefox is already running, but I can't find it running. How do I do so or in any case close the already running Firefox process?

When I attempt to open Firefox instead of Firefox opening, an error message appears saying "Firefox is already running but isn't responding. To open another window please close the existing Firefox process or restart the system.", but I can't find that process of Firefox in order to kill it, and after restarting the system there is still the problem. I have found an emergency fix to at least get online, and that is to use"Firefox_Profile_Manager" in the start menu's "run" start menu, but the
Firefox that then opens is that one doesn't carry over what I had in my bookmarks but starts bookmarks anew.

Sounds like it is hanging when you exit and later try to restart Firefox.
* How to stop the running Firefox process
** In Task Manager, does firefox.exe show in the '''Processes''' tab?
** See: http://kb.mozillazine.org/Kill_application
**Windows 7 users: http://www.techrepublic.com/blog/window-on-windows/reap-the-benefits-of-windows-7s-task-manager/2576
* What may cause Firefox to hang at exit
**Windows 7 Task Manager: http://www.techrepublic.com/blog/window-on-windows/reap-the-benefits-of-windows-7s-task-manager/2576
** http://support.mozilla.com/en-US/kb/Firefox+hangs
** http://kb.mozillazine.org/Firefox_hangs
** https://support.mozilla.com/en-US/kb/Firefox+is+already+running+but+is+not+responding
* You may need to try Firefox Safe Mode
** You may need to use '''Safe Mode''' to locate the problem: ***See: http://kb.mozillazine.org/Safe_Mode
***Firefox 4 users, hold the Shift key while clicking the Firefox 4 desktop icon to enter Safe Mode.
***Firefox Safe Mode is a diagnostic mode that disables Extensions and some other features of Firefox.
****In Firefox 4, Safe Mode also disables Plugins and Hardware Acceleration.
****If you are using a theme, switch to the DEFAULT theme: Tools > Add-ons > Themes '''before''' starting Safe Mode (In Firefox 4, Tools > Add-ons > Appearance). See: http://support.mozilla.com/en-US/kb/Using%20themes%20with%20Firefox#w_managing-themes-and-personas
****When entering Safe Mode, do not check any items on the entry window, just click "Continue in Safe Mode".
****Test to see if the problem you are experiencing is corrected.
*** If the problem does not occur in Safe-mode then disable all of your Extensions and Plug-ins and then try to find which is causing it
***#by enabling '''one at a time''' until the problem reappears.
***#You can also enable a few at a time (3-5), keeping track of what you just re-enabled to see if the problem re-occurs; this will help narrow down the possibilities if you have a large number of add-ons.
***#'''You MUST close and restart Firefox after EACH change''' via File > Restart Firefox (on Mac: Firefox > Quit).
***#You can use "Disable all add-ons" on the Safe Mode start window.
**See the following for more information
*** http://support.mozilla.com/en-US/kb/Troubleshooting+extensions+and+themes
*** http://support.mozilla.com/en-US/kb/Troubleshooting+plugins
*** http://support.mozilla.com/en-US/kb/Basic+Troubleshooting
 
 
'''You need to update the following:'''
*Adobe Shockwave for Director Netscape plug-in, version 11.5
*Adobe PDF Plug-In For Firefox and Netscape "9.3.2"
*Shockwave Flash 10.2 r153
*Next Generation Java Plug-in 1.6.0_17 for Mozilla browsers
#'''''Check your plugin versions''''' on either of the following links':
#*http://www.mozilla.com/en-US/plugincheck/
#*https://www-trunk.stage.mozilla.com/en-US/plugincheck/
#*'''Note: plugin check page does not have information on all plugin versions'''
#*There are plugin specific testing links available from this page:
#**http://kb.mozillazine.org/Testing_plugins
#'''Update Shockwave for Director'''
#*NOTE: this is not the same as Shockwave Flash; this installs the Shockwave Player.
#*Use Firefox to download and SAVE the installer to your hard drive from the link in the article below (Desktop is a good place so you can find it).
#*When the download is complete, exit Firefox (File > Exit)
#*locate and double-click in the installer you just downloaded, let the install complete.
#*Restart Firefox and check your plugins again.
#*'''Download link and more information''': http://support.mozilla.com/en-US/kb/Using+the+Shockwave+plugin+with+Firefox
#'''Update Adobe Reader (PDF plugin):'''
#*From within your existing Adobe Reader ('''if you have it already installed'''):
#**Open the Adobe Reader program from your Programs list
#**Click Help > Check for Updates
#**Follow the prompts for updating
#**If this method works for you, skip the "Download complete installer" section below and proceed to "After the installation" below
#*Download complete installer ('''if you do NOT have Adobe Reader installed'''):
#**SAVE the installer to your hard drive (save to your Desktop so that you can find it after the download). Exit/Close Firefox. Run the installer you just downloaded.
#**Use either of the links below:
#***https://support.mozilla.com/en-US/kb/Using+the+Adobe+Reader+plugin+with+Firefox ''(click on "Installing and updating Adobe Reader")''
#***''Also see Download link''': http://get.adobe.com/reader/otherversions/
#*After the installation, start Firefox and check your version again.
#'''Update the [[Managing the Flash plugin|Flash]] plugin''' to the latest version.
#*Download and SAVE to your Desktop so you can find the installer later
#*If you do not have the current version, click on the "Player Download Center" link on the "'''Download and information'''" or "'''Download Manual installers'''" below
#*After download is complete, exit Firefox
#*Click on the installer you just downloaded and install
#**Windows 7 and Vista: may need to right-click the installer and choose "Run as Administrator"
#*Start Firefox and check your version again or test the installation by going back to the download link below
#*'''Download and information''': http://www.adobe.com/software/flash/about/
#**Use Firefox to go to the above site to update the Firefox plugin (will also install plugin for most other browsers; except IE)
#**Use IE to go to the above site to update the IE ActiveX
#*'''Download Manual installers'''.
#**http://kb2.adobe.com/cps/191/tn_19166.html#main_ManualInstaller
#**Note separate links for:
#***Plugin for Firefox and most other browsers
#***ActiveX for IE
#'''Update the [[Java]] plugin''' to the latest version.
#*Download site: http://www.oracle.com/technetwork/java/javase/downloads/index.html (Java Platform: Download JRE)
#**'''''Be sure to un-check the Yahoo Toolbar option during the install if you do not want it installed.
#*Also see "Manual Update" in this article to update from the Java Control Panel in Windows Control Panel: http://support.mozilla.com/en-US/kb/Using+the+Java+plugin+with+Firefox#Updates
#* Removing old versions (if needed): http://www.java.com/en/download/faq/remove_olderversions.xml
#* Remove multiple Java Console extensions (if needed): http://kb.mozillazine.org/Firefox_:_FAQs_:_Install_Java#Multiple_Java_Console_extensions
#*Java Test: http://www.java.com/en/download/help/testvm.xml

How can I stop from getting the "Firefox is already running" error message when trying to open links and FF has already been opened through a symbolic link?

I use symbolic links and program shortcuts as a way to easily open different Firefox profiles ie. one for casual/personal use and another for work. This works well, but I get the "Firefox is already running, but is not responding" error message if I try to open external links with FF as my default browser. FF is actually open and running fine, but I guess it doesn't acknowledge this fact because of how I'm originally starting the process.
I wasn't able to add the symbolically linked executables to the default program pane. Is there a way to bypass this error or other way to fix this?
The solution to the question linked below is what I'm using to open the different FF profiles.
http://superuser.com/questions/255312/pin-same-app-multiple-times-in-windows-7

hello, this is probably happening when you run the default profile with the -no-remote switch.
http://kb.mozillazine.org/Profile_in_use

I try to open Firefox. Get error message saying Firefox is already running and needs to close - another error message say Firefox can't open

Turned on laptop (rebooted) after being away from it for a few hours. Went to open my home page. Error message popped up saying Firefox is already running and must be closed. I closed it and another error message popped up saying Firefox can't open - incomplete or missing files.
I went into Processes to close Firefox. Selected 'end process' but nothing happened.
Tried to use Internet Explorer but it just gets hung up. Cannot access anything.
And, because I can't open Firefox, I can't go a refresh.
Everything was working just fine a few hours ago.
Any thoughts?

What is the computer system and Firefox on the bad computer?
Separate Issue;
Your System Details on this computer shows;
Multiple versions of your Adobe programs.
Having more than one version of a program may cause issues.
Go to '''adobe.com''' and download the full installers after removing
all of the old programs.
Start '''[https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Firefox in Safe Mode]''' {web Link} by holding down the '''<Shift> ''(Mac Options)'' ''' key, and then starting Firefox. Is the problem still there?
This is not a cure but will make it easier if Firefox locks up in Windows.
'''https://support.mozilla.org/questions/997866''' {web link}

Error: "firefox is already running". Won't start until I stop process on task mgr.

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