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Can't open Firefox

  • 12 replies
  • 5 have this problem
  • 141 views
  • Last reply by Bcamp

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I've used Firefox for years with no issue. Suddenly, I can't open it no matter what I try. Another family member is now using my laptop and uses Chrome for his browser and may have inadvertently changed something. So, I tried uninstalling it and reinstalling but the message comes back that I have to close the current version first. But, I can't access it or even see that it's open.

I've used Firefox for years with no issue. Suddenly, I can't open it no matter what I try. Another family member is now using my laptop and uses Chrome for his browser and may have inadvertently changed something. So, I tried uninstalling it and reinstalling but the message comes back that I have to close the current version first. But, I can't access it or even see that it's open.

Chosen solution

Did Firefox work normally when you ran it in Windows' Safe Mode with networking?

Autoruns has a bunch of tabs. Logon is one of the more interesting ones, since those are the things that Safe Mode is most likely to bypass. However, I'm not sure it's safe for you to uncheck things without finding out more about what they are.

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If you get the message that you have to close Firefox even the first time after you restart Windows, it can indicate a problem with permissions on your settings files, or that a lock file is present.

There is a general help article: "Firefox is already running but is not responding" error - How to fix.

Regarding the lock file, I don't know if that is still an issue in recent versions of Firefox, but you can check for it this way:

Open your currently active Firefox profile folder in Windows Explorer. You can do that from any of these starting points:

  • A Windows Explorer window, you'll paste the following shortcut path into the address bar of the window
  • The Windows Run dialog (Windows key + R)
  • The Windows 7 Start menu search box

Type or paste the following and press Enter to it:

%APPDATA%\Mozilla\Firefox\Profiles

In that folder, do you see a semi-randomly-named folder? If so, click into it. (If you find multiple such folders, find the one that was most recently updated.)

These are your Firefox settings. Please do not delete any files here without making a backup first, except for the following file.

Look for a file named parent.lock and right-click > Delete it. If it can't be deleted, that may be the cause of the problem, but hopefully it can be deleted.

If it's not there, then please see the general help article for other suggestions.

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If you have problems removing the parent.lock file, start the computer in Safe Mode and try again.

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I have tried everything suggested with no success. I found a parent.lock file and deleted it. I ended all firefox tasks in Task Manager, however every time I open it again, there was still a FF task. The last time I ended the task tree and it seems to be gone.I looked at the "read only" box. It was highlighted but not checked. I removed the highlight.

Still not able to access FF.

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Could you try from the Windows 7 Start menu search box. You just need to type or paste

firefox.exe 

and pause to see what shows up as a match. Usually there's just one Firefox executable, and you can press Enter (or click it) to run it. Does that work any better than the shortcut?

If you have two or more matching executables, it's possible you have both the 32-bit and 64-bit Firefox installed simultaneously, or a combination of version numbers, which may be an issue.

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Boot the computer in Windows Safe mode with network support to see if that has effect in case security software is causing problems.

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Pasted firefox.exe into search box. Result is the word firefox underlined. Back to task manager. 2 processes running; deleted 1 of them multiple times; keeps recurring.

Reviewed opening in safe mode. Running Wins 7 and this was supported for Wins 2000 and later. No MS support due to age of OS and laptop.

Reviewed previous versions and compatibility but not sure of consequences.

Still no access as download says a version is still running. HELP!!

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Bcamp said

Pasted firefox.exe into search box. Result is the word firefox underlined.

Usually Windows 7 will display matches on a panel in place of the Start menu above the search box. The Firefox program file will have the Firefox icon next to it, and may appear in the Programs category or the Files category. You didn't see anything like that?

Back to task manager. 2 processes running; deleted 1 of them multiple times; keeps recurring.

Firefox is a multiprocess program. One process is for the interface and one is for the web content. So that is normal and if you kill the web content process, Firefox will re-launch it.

I think the main problem is that Firefox is starting but there's no visible window. Do you get a Taskbar icon with a thumbnail of your home page, or zero indication that Firefox is running?

Reviewed opening in safe mode. Running Wins 7 and this was supported for Wins 2000 and later. No MS support due to age of OS and laptop.

Windows 2000 was released in 2000, before Windows XP and Windows Vista. Windows 7 is much newer than Windows 2000 and definitely can be started in Safe mode with networking.

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Usually Windows 7 will display matches on a panel in place of the Start menu above the search box. The Firefox program file will have the Firefox icon next to it, and may appear in the Programs category or the Files category. You didn't see anything like that?

No.

Do you get a Taskbar icon with a thumbnail of your home page, or zero indication that Firefox is running?

No indication

definitely can be started in Safe mode with networking.

Should I do that now or try something else? What do I do in SM? And, what happens when I close SM?

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Windows Safe Mode bypasses some programs and services that normally start automatically. If Firefox works normally in Windows Safe Mode, then those bypassed programs/services come under suspicion for interfering with Firefox.

I'm not personally familiar with the easiest way to figure out what those prgorams/services are. However, I sometimes use the Autoruns program to check what's set to happen at startup when there seems to be a lot of junk slowing down Windows: https://docs.microsoft.com/en-us/sysinternals/downloads/autoruns

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I've exhausted my technical ability to resolve this. I don't understand what to do with the autoruns. I clicked on it but not sure how to proceed :( Thanks for your help.

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Chosen Solution

Did Firefox work normally when you ran it in Windows' Safe Mode with networking?

Autoruns has a bunch of tabs. Logon is one of the more interesting ones, since those are the things that Safe Mode is most likely to bypass. However, I'm not sure it's safe for you to uncheck things without finding out more about what they are.

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It did open in Safe Mode with no problem and I noticed there were 2 profiles. I didn't know which was good so I chose one and deleted it. When I rebooted, I chose it again and refreshed it per FF prompts and, amazingly, it finally opened correctly and I still have all my bookmarks!

How frustrating but so happy to be using FF again as I don't like the interfaces for other browsers. Thanks!!!