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Forefox won't work after installing XAMPP, just keeps saying there is already an instance running even though there isn't

  • 10 replies
  • 1 has this problem
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  • Paskiausią atsakymą parašė FredMcD

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Firefox will no longer run on my machine. I'm on vista home premium 64bit.

I installed XAMPP on my pc so I could run wordpress on it. XAMPP then installs apache server, mysql and php on the pc. Once this was done I discovered that I couldn't use firefox or my windows mail anymore.

Both programs kept saying there was already an instance running, even though there wasn't. I rebooted the pc but still had the same problem, so I uninstalled XAMPP / wordpress etc and tried again, still no luck.

I uninstalled firefox then downloaded it again, it still tells me that there is already an instance of firefox running and it just won't start.

I've tried rebooting several times but can't get firefox to work.

I sorted out the mail problem by renaming the windows mail folder then importing the messages. Maybe a similar trick would work with firefox?

Any help greatly appreciated.

Firefox will no longer run on my machine. I'm on vista home premium 64bit. I installed XAMPP on my pc so I could run wordpress on it. XAMPP then installs apache server, mysql and php on the pc. Once this was done I discovered that I couldn't use firefox or my windows mail anymore. Both programs kept saying there was already an instance running, even though there wasn't. I rebooted the pc but still had the same problem, so I uninstalled XAMPP / wordpress etc and tried again, still no luck. I uninstalled firefox then downloaded it again, it still tells me that there is already an instance of firefox running and it just won't start. I've tried rebooting several times but can't get firefox to work. I sorted out the mail problem by renaming the windows mail folder then importing the messages. Maybe a similar trick would work with firefox? Any help greatly appreciated.

Chosen solution

Do you have the Firefox icon on your quick launch? Right click on it, and select Open New Window. Sometimes this works. If it opens, close it by Menu > File > Exit.

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All Replies (10)

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Open your Firefox Profile folder and see if the parent/lock file is "stuck" or "hung". That file is supposed to be deleted as Firefox closes - properly closes. If it is in your Profile folder, delete that file and then try to launch Firefox.

https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

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Start Firefox in Safe Mode {web Link} by holding down the <Shift (Mac Options) > key, and then starting Firefox. Is the problem still there?

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Doesn't help. Same problem

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There is no parent/lock file or setting and there is no profile folder so I can't check this. However I would have thought yhat

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I would have thought that removing Firefox woukd have removed this file also?

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I tried uninstalling it again, I even removed all registry entries for mozilla then re-installed firefox but I just get the same message that firefox can't start because there is already an instance running - even though there are NO Firefox files on my pc. This is driving me nuts. I can't be the only person on the planet that has had firefox issues after installing XAMPP (even though it's now uninstalled).

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Create a new profile as a test to check if your current profile is causing the problem.

See "Creating a profile":

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

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Chosen Solution

Do you have the Firefox icon on your quick launch? Right click on it, and select Open New Window. Sometimes this works. If it opens, close it by Menu > File > Exit.

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Eventually, I just removed ALL the mozilla files on the pc then reinstalled firefox. This worked, but I've lost all my bookmarks. I tried restoring stuff from the recycle bin hoping to get them back but no luck yet, probably because I don't know what the file is actually called. Thanks for all your help.

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If you deleted the user profile, then everything is gone. If the data is still in the recycle bin, do this. On the desktop, create a folder and call it Old Firefox. Open this folder. Now open the recycle bin. Locate only the profile folders in the bin. Select all of them. Now drag those from the recycle bin to the Old Firefox folder you opened.

BTW, see if there is such a folder there now.

https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles