Firefox is already running but is not responding

[matthewforu]

if your Browser (Mozilla Firefox) is already but not running but not responding . to troubleshoot this issue:

Follow the steps to given below:
In Windows Vista If you are receiving the above error message while attempting to start Firefox, try to restart the program. If the problem persists, do the following:
1. Restart your computer.
2. Select the Start Menu in the Windows Taskbar.
3. In the Search box, enter the following:
%APPDATA%
4. Press Enter.
5. From the Application Data folder, navigate to Local\VirtualStore\Program Files\Mozilla Firefox.
6. Delete the file xpicleanup.dat.
7. Restart Firefox.
In Windows XP
1. Click on the Start button and select Search to open the Search Results window.
2. On the left side of the Search Results window, click on the All files and folders link.
3. Click to expand the More advanced options list.
4. Put a check mark next to Search system folders, Search hidden files and folders, and Search subfolders.
5. In the All or part of the file name field, type xpicleanup.dat.
6. Click Search to begin the search.
7. If any results are returned, delete them.
8. Restart Firefox.

[Rameez.J]

Thread Moved.

[WMBrown]

Instead of restarting your computer, you can also use the Windows Task Manager to close the existing Firefox process:

1. Right-click on an empty spot in the Windows task bar and select Task Manager (or press Ctrl+Shift+Esc).
2. When the Windows Task Manager opens, select the Processes tab.
3. Select the entry for firefox.exe (press F on the keyboard to find it) and click End Process.
4. Click Yes in the "Task Manager Warning" dialog that appears.
5. Repeat the above steps to end any additional firefox.exe processes, if more than one entry is found, then exit the Windows Task Manager.
6. Start Firefox normally.

Note: If this is a recurring problem, see Firefox hangs - Hang at exit for possible causes and solutions.

If restarting the computer didn't help, it may be that Firefox previously exited without deleting the lock file.

1. Restart your computer. After it restarts, don't try to start Firefox.

2. Open the profile folder.
* For information on finding your profile folder, see Profiles.

3. Delete the lock file parent.lock.parentlock
* If you attempt to delete the parent.lock file and receive the error, "Cannot delete parent: The file or directory is corrupted and unreadable", restart the computer and run the error-checking tool Chkdsk (Windows 2000, XP) or ScanDisk (Windows 98, ME)

[Dottore]

Geez, I searched and searched and bloody searched endlessly to find a solution to this problem but in the end, I resolved it myself.

What really annoyed me was that the vast majority of advice was centered around closing Firefox via Task Manager/Processes or the even more arcane fiddlings with 'Run' and various commands but NOT on how to permanently fix the problem.

Firstly, I have no real idea how I instigated the 'Firefox is already running...' error message, albeit, I did at various times, open new windows to access other sites while I was at a particular Firefox page.

These actions may or may not have caused the ensuing error message. Coincidentally or otherwise, it was around those times that the error message first started to appear.

Throughout my hours of searching and subsequent readings of numerous sites purporting to 'have the answer' to my query, one word kept appearing, Profile/s.

Long story short, what I did was this:

goto My Documents/Mozilla/Firefox/Profiles...and DELETE the Profile. Job done!

Btw, the reason I decided to delete this file was that I noticed that it did not have the same file name as the Profile file name in c:\Documents and Settings\'User name'\Local Settings\Mozilla\Firefox\Profiles\'whatever name'.default.

Worked for me, hope it does for you, as well

Dottore

PS: The OS is Windows XP SP3.

[toadzapper]

I have windows xp sp3, but this probably is similar in windows vista also.

In short…My problem was that I deleted an old, unused windows user profile from my "C:\Documents and Settings\" folder. Apparently, my Firefox profile was in one of those folders, so firefox could no longer access the profile... resulting in the error message. (This is apparently a 5 year-old bug, and so the error message is incorrect, and doesn't provide insight into the problem as being a "profile" error).

Things that did NOT work:
1. In windows task manager, I did NOT have a "firefox.exe" process running, so that wasn't the issue.
2. I did NOT have any *.lock files to delete.
3. I tried deleting all firefox profiles (not permanently, but to recycle bin). Restarted firefox, but still same error.
4. Uninstalled firefox (but did not remove old setting files and such). Reinstalled. Ran firefox, same error.
5. Maybe if I removed firefox AND any old settings, I would probably have a clean firefox working, but I wanted to keep old settings.

Solution:
1. go to Start > Run… > type in "firefox.exe -ProfileManager"
2. you probably have more than one profile. chose a profile, the click "start firefox". (I had 2 profiles).
3. if you only have 1 profile, I presume you can just delete this non-working one and create a new one (but I didn't try this).
4. My 1st profile resulted in the same error appearing as before (ie. "firefox already running…")
5. But, when I chose the 2nd profile and started firefox, it started just fine, BUT, with many of my previous browser settings and add-ons gone. (at this point I didn't care, I was just glad to get firefox to work).

Digging deeper...
1. I was previously trying to synchronize my firefox profile on multiple pc's using dropbox, via the add-on extension "Profile Manager and Synchronizer".
2. At the bottom right corner of the firefox window is the Profile manager, with the name of the profile currently in use. Right click on it and go to "options…"
3. You can see a list of your profiles, and you can see which one is the default one. If you are satisfied with your currently running profile, just set is as the default.
4. My default profile was in a folder that no longer existed, so I copied all the files from the location of the working profile, into a newly created folder in "C:\Documents and Settings\*User*\Application Data\Mozilla\Firefox\Profiles\", and then selected the non-working profile and clicked the "edit profile name/path" option to point firefox to my newly created folder.
5. Now when I went to Start > Run… > "firefox.exe -ProfileManager", and chose my previously non-working profile, it worked.
6. Now, Firefox knows the directory location of my profile.
7. I will now proceed to screw with my profiles again, and attempt to sync. Hopefully with less disastrous results.

[plasterwoman]

Hello!

I did a very stupid thing last night , in an attempt to speed up Firefox, I went here - ' C:\Documents and Settings\DrBicks\Local Settings\Application Data\Mozilla\Firefox\Profiles\' and deleted ALL the 0mox1wz2.default folders.
In the process rendering Firefox not launch whatsoever, continally showing the alert box with the message - "Firefox is already running but not responding. To open a new window, you must first close your existing Firefox process, or restart your system".

I fear I may have lost ALL my bookmarks in the process.

However, in the following folder - 'C:\Documents and Settings\DrBicks\Application Data\Mozilla\Firefox\Profiles' there are .MFL files approximately 3.5MB each. I have a suspicion my bookmarks could be in there ??


If any one has had a similar experience or have aNY solutions to this problem, it will be greatly received.

Yours Sincerely,

[Rudra.J]

Open Task Manager and see if Firefox is still in the process list. If it is, you need to end task it and then try to start firefox again. This happens when you have opened a lot of tabs and firefox consumes a lot of memory. Then when you quit firefox with all the tab opened, it takes some time to dump those tabs in a file so that they could be restored when you next start firefox...

[kitestore]

Hello!

I did a very stupid thing last night , in an attempt to speed up Firefox, I went here - ' C:\Documents and Settings\DrBicks\Local Settings\Application Data\Mozilla\Firefox\Profiles\' and deleted ALL the 0mox1wz2.default folders.
In the process rendering Firefox not launch whatsoever, continally showing the alert box with the message - "Firefox is already running but not responding. To open a new window, you must first close your existing Firefox process, or restart your system".

I fear I may have lost ALL my bookmarks in the process.

However, in the following folder - 'C:\Documents and Settings\DrBicks\Application Data\Mozilla\Firefox\Profiles' there are .MFL files approximately 3.5MB each. I have a suspicion my bookmarks could be in there ??


If any one has had a similar experience or have aNY solutions to this problem, it will be greatly received.

Yours Sincerely,

Thanks all for contributing to this thread. Lots to read in this forum but I like it.

[doorsmorr]

I joined this site specifically to post in this thread since it was giving me a headache! Okay, I was having this same problem that everyone seems to be having, but no ones advice helped. What I had to do was go into your profiles folder:

My Computer \ Local Disk C: \ Users \ (your username) \ AppData \ Roaming \ Mozilla \ Firefox \ Profiles

Right click the profile that is there (the same will work if you accidentally deleted your profile and this folder is empty, just right-click in the open window). Click the Previous Versions tab, find the earliest profile, the click restore. Voila!!

Somehow my anti-virus picked something up in this folder as a virus and naturally, I deleted it. My Firefox would not open and I kept getting this error message. After restoring my profile back to an earlier version it works now.

Depending on how far back you go, you may lose bookmarks that you have added since the date of the restore, but it's a small price to pay to fix Firefox. I hope this helps someone and look forward to become a part of this community!

[Goldsands]

Toadzapper
Thank you so much. I am so grateful for the solution you posted.

[gerry252]

Hi Guys,
I have had this problem sin installing new Windows 7. Works fine when I login as local admin (administrator account). When I log in as self (normal user) I get the dreaded error message. Like Dottore, I found most of the fixes trivial and useless, I am sure they work for the particular root causes, but not for mine.
As all else did not work, eventually I fixed it as follows:
NOTE: this applies for Windows 7, it might work for other Windows with suitable changes to paths etc.
1. In WIndows 7 click 'start' button, in the search field type, 'firefox.exe -profilemanager'. (this is standard stuff mentioned elesewhere)
2. Form Profile manager create a new profile with memorable name, I called mine 'bob', so the profile was creadted as wx4donqh.bob. This was only so that I can differentiate it from other profiles.
3. At this stage, and only if you have a saved (backup) profile, open wx4donqh.bob delete the contents, if any; open you backed up profile copy all the contents and paste in to the new profile. So far all this has been metioned elsewhere.
4. This is where I solved my roblem - In Notepad open the file called 'Profiles' in C:\Users\%user_name%\AppData\Roaming\Mozilla\Firefox. This may look like this:
[General]
StartWithLastProfile=1

[Profile0]
Name=Default
IsRelative=1
Path=Profiles/58gwmgd0.default User

You need to edit it to look like this:
[General]
StartWithLastProfile=0

[Profile0]
Name=58gwmgd0.bob
IsRelative=1
Path=Profiles/58gwmgd0.bob
Thats it.

I know this wont work for every one and may I suggest some of the simpler solutions be tried first. It worked for me for my particular circumstances. I hope it helps you.

[jesster1000]

Mozilla Firefox is a good internet browser. Its new version Firefox 4 is creating some problems like stop working without showing any error. The best way to solve it is by replacing it with new version Firefox 4.07 beta. It’s a good one.
Other way to solve this is by ust uninstalling Firefox and then run a cleaner like cc cleaner, Reginout cleaner, etc. and restart your computer. Then install Firefox 3.06. Then, it will never create that kind of problems.
There is another reason. May be your computer is corrupted by virus. So you need to use updated antivirus and full scan your computer.

[Vj9]

Dear toadzapper,
Thank you very much for your excellent solution to this problem.