Firefox is already running, but is not responding.

Ever since upgrading to FF 29, I get this error message just about every time I close and then re-open Firefox. With 28 I got the message sometimes, but with seeing this every time (and having to manually kill the firefox.exe process) this has grown quite frustrating to the point I am considering not using Firefox. I've already been through the various forums and help sites, I have disabled all of my add-ons, deleted extensions, etc to no avail. I still get this message almost every close/open cycle. Also this happens on multiple Windows 7 machines so its not isolated to one environment. Is this a known issue and what is being done to resolve it?

Thanks Moses - I agree that is a workaround, but unfortunately its not an acceptable one. Being able to clear history/cookies is very important. Luckily I have found that the latest beta 30.0b9 seems to have fixed this problem. I installed this client and havent gotten the error since. If anyone is having this problem, try the beta here: http://www.mozilla.org/en-US/firefox/channel/#beta and let us know if it fixes the issue.

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Frequently when I open Firefox it says Firefox is already running but is not responding. I have to go to the task manager, find Firefox and close the process before I can get firefox to load.

Those are all the details I have

There is an article about this problem see:
* [[Firefox is already running but is not responding]]

When I click to open firefox it says that "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" and I've tried to shut down and restart my computer but it keeps

when i click to open firefox it says that "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." and I've tried to shut down and restart my computer but it keeps showing the same message. I've even uninstalled Firefox and then reinstalled in the hopes that the problem would be solved but it this message is still popping up. What can I do to solve this problem?
== This happened ==
Just once or twice
== I was on facebook trying to upload pictures yesterday. ==
== User Agent ==
Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0; InfoPath.1)

Do you have a profile lock file in your profile folder? If so, delete it and see if TB runs properly:
http://kb.mozillazine.org/Profile_in_use#Remove_the_profile_lock_file

I close firefox and try to open it again later, it WON'T and says, "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." Firefox isn't running .

After I turn on my laptop and click on firefox it works fine and it opens THE FIRST TIME. So can you help? i DON'T WANT TO RESTaRT my computer everytime and sometimes have to clsoe firefox b/c I'm typing paper and computer goes slow.

Sounds like a "hang at exit" problem. There are several possible causes for that error. See:
* 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
* What may cause Firefox to hang at exit
** http://support.mozilla.com/en-US/kb/Firefox+hangs (see "Hang at exit" section)
** 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: http://support.mozilla.com/en-US/kb/Safe+Mode
**Firefox Safe Mode is a diagnostic mode that disables Extensions and some other features of Firefox. If you are using a theme, switch to the DEFAULT theme: Tools > Add-ons > Themes '''before''' starting Safe Mode. 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 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

Firefox is OPEN and working fine, but when I click a link in Thunderbird I get '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.'

If I click a link on my desktop or in any other program (while Firefox is open and running), I get this message: "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." There's about a billion links for this if you Google it, but they all say that Firefox wasn't shut down properly. (OK, maybe not ALL of them, but if the needle is in that haystack, I haven't yet found it.) That's not the issue in my case since I haven't shut FF down at all.
== This happened ==
Every time Firefox opened
== IDK

This began to happen to me when I tried to run two separate profiles simultaneously on the same installation of firefox with -no-remote

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.

I deleted the profile and firefox4 and then downloaded firefox4 again. But when i click firefox it says 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.HELP!

somehow i couldn't get rid of one website called www.searchqu.com/405 set as my homepage... I tried all solutions given to change the homepage but whenever i restarted firefox that homepage used to come automatically.. So, I deleted the profile (even from recycle bin!!) and deleted the firefox and downloaded it again hoping to get my problems fixed (which didn't happen!) because i'm getting dialog box saying- 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.

You don't say which operating system you have installed?
Assuming it's Windows, right click a blank part of the Windows Taskbar and go to Task Manager. Then click the ''Processes ''tab, find '''firefox.exe''' and then right click it and choose '''End Process'''.

Everytime I try to open firefox i keep getting this message "Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your computer"

i have restarted my computer and i have uninstalled firefox and re-installed it but i still get the same message i have also tried safe mode and it still has not worked, and i have recently gotten rid of a trojan virus

Do you still have a [http://kb.mozillazine.org/Profile_folder_-_Firefox Firefox Profile Folder] ?
* [[Firefox is already running but is not responding]]
* http://kb.mozillazine.org/Profile_in_use

When I try to access Firefox I get this message: "Firefox is already running, but is not responding. To open a new windwo, you must first close the existing Firefox process, or restart your computer."

When I click on Firefox I get a window that says: "Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your computer." I can't see where anything is running on firefox. I restarted the comuter and I shut down the computer. I also ran a full scan of the computer.

Sorry I am a PC user but have you seen
* [[Firefox is already running but is not responding]]
Firefox will be hanging for some reason. The quick solutions to kill the process and try again. The next step is to try to see if it will start and exit normally a couple of times, if so the problem is solved. If not the reason needs further investigation.
See [[firefox hangs]]
An immediate likely culprit after repeated problems are the duplicate session restore files, as discussed in the above KB article.

Iget this when I try to open a session....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.task mngr shows no open firefox processes.

I get this when I try to open a session....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.The task manager shows no open Firefox processes.I had two users on this laptop running Firefox and I tried deleting the program on both users. I then downloaded the newest version, installed it and I still get the error message as before. HELP!!!! I loved the browser program when it was working before and would rather use it than other browsers.

See "Hang at exit":
* http://kb.mozillazine.org/Firefox_hangs
* https://support.mozilla.com/kb/Firefox+hangs

I keep getting this message after closing Firefox and attempt to reopen-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.

I keep getting this message after closing Firefox and attempt to reopen-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.

See:
* http://kb.mozillazine.org/Recovering_a_missing_profile
* http://kb.mozillazine.org/Profile_in_use

When I try to start Firefox I get 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.

I get this message when I try to start Firefox after first logging on after turning on the computer.
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.
Have rebooted. Works when Administrator logs in, just does this in my user profile. Have also re-intalled. Mo change in my User account.
Firefox was working fine for the last 3 1/2 years. Any suggestions?

Firefox is "hanging at exit" when you exit/quit Firefox. 
#Stop the Firefox process:
#*[http://kb.mozillazine.org/Kill_application Mozillazine - Kill application]
#*Windows 7 users click [http://www.techrepublic.com/blog/window-on-windows/reap-the-benefits-of-windows-7s-task-manager/2576 here]
#*Mac users: http://techheavy.com/2011/02/the-mac-task-manager/
#Why Firefox may hang:
#*[http://support.mozilla.com/en-US/kb/Firefox+hangs Firefox hangs] (see Hang at exit)
#*[http://kb.mozillazine.org/Firefox_hangs Firefox hangs (Mozillazine)] (see Hang at exit and Closing Firefox properly)
#*[https://support.mozilla.com/en-US/kb/Firefox+is+already+running+but+is+not+responding Firefox is already running but is not responding]
#Use Firefox Safe Mode to find a problem with an Extension or Plugin:
#*Don't check anything when entering Safe Mode, just continue
#*If the problem does not occur in Safe Mode it is probably and Extension or Plugin causing the problem
#*See:
#**[[Safe Mode]] and [http://kb.mozillazine.org/Safe_Mode Safe Mode (Mozillazine)]
#**[http://support.mozilla.com/en-US/kb/Troubleshooting+extensions+and+themes Troubleshooting extensions and themes]
#**[http://support.mozilla.com/en-US/kb/Troubleshooting+plugins Troubleshooting plugins]
#**[http://support.mozilla.com/en-US/kb/Basic+Troubleshooting Basic Troubleshooting]
'''If this reply solves your problem, please click "Solved It" next to this reply when signed-in to the forum.'''

Firefox keeps hanging up and freezing. I get this message. "Firefox is already running, but is not responding. To open a new window, you must first close the existing--what a mess.

No matter how many times I open and close, firefox hangs up after surfing a few pages. When I look at task master, firefox is using up hundreds of thousands of kb, causing the processor to stall at 100%. I do not have this problem when surfing with IE. I have the latest version of firefox. I never had this problem with version 5. It keeps getting worse with each "update".

See [[Firefox is already running but is not responding]]
Obviously firefox should not hang after surfing a few pages. I have Firefox installed on an XP including firefox 6.0.2 and do not have problems.
See also
* [[Firefox consumes a lot of CPU resources]]
* [[High memory usage]]
Have a read of the above linked articles. The first thing to do is to try to get firefox to behave more normally
#Use [[safe mode]]
#* but do not make changes when you have the window with a list of options just click continue
# if using safe mode does not solve the problem also
#* make sure you use the default theme
#* disable all pluggins
Note by keying in ''about:memory'' into the location bar you will get a report, which includes more info as you roll the mouse pointer over items, that should help indicate where all the memory is being used.

I get "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 when trying to open Firefox.

I have found this particular problem addressed in the assistance pages, and have tried all of the suggestions (trying to delete parent.lock from the profile, restoring the profile, etc.). Nothing works. What's next?

For possible causes see [[Firefox is already running but is not responding]].

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. How do I fix this? I am ready to go back to internet explorer!

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.
This box appears and then firefox quits...never opens.
I have uninstalled, and loaded firefox 5 times and never got it to run.

See [[Firefox is already running but is not responding|Firefox is already running but is not responding]].

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. I have tried

After deleted profile my Firefox will not start
Message - 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.
I have tried – Restarting - Checking control panel for active firefox.exe –Uninstal l- Reinstall- and run CCleaner. All without any result
Can You help me? Are there any other processes that can be running?
Is there any cleaning tool available?
Best Regards, Pelle

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, but is not responding.

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