killing stubborn processes

cokedude · Jun 19, 2025

Sometimes I have a very stubborn process that I can not kill with task manager, taskkill, or wmic. This usually happens to chrome or firefox. The best guide I have found has been this. Does anyone have any other ideas for killing stubborn processes?

No window opens when Firefox is clicked on, but runs in the background for each time it is clicked. Cursor repeatedly flickers or spins after opening. | Firefox Support Forum | Mozilla Support

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1. Try to kill with task manager.
Does not work.

2. Try to kill with taskkill. taskkill does point out there is an issue with a parent process. So also try to close that.
Does not work.

Code:

C:\>taskkill /f /t /PID 10296
ERROR: The process with PID 10296 (child process of PID 11824) could not be terminated.
Reason: Access is denied.

C:\>taskkill /IM firefox.exe /f /t
ERROR: The process with PID 10296 (child process of PID 11824) could not be terminated.
Reason: Access is denied.

C:\>taskkill /f /t /PID 10296
ERROR: The process with PID 10296 (child process of PID 11824) could not be terminated.
Reason: Access is denied.

C:\>taskkill /f /t /PID 11824
ERROR: The process "11824" not found.

3. Try to kill with wmic.
Does not work.

Code:

C:\>wmic process where name='firefox.exe' delete
Deleting instance \\GHOST\ROOT\CIMV2:Win32_Process.Handle="10296"
ERROR:
Description = Access denied

One other interesting thing I found while google searching is this. It gives you the ability to look at all your columns in wmic.

Code:

wmic process where name="firefox.exe" get /format:htable > c:process.htm

Does anyone else have any suggestions?

Ghot · Jun 19, 2025

@cokedude

Maybe I don't understand the question.
Just "close" Firefox.

You understand that Firefox needs to run all those other instances?

cokedude · Jun 19, 2025

Ghot said:
@cokedude

Maybe I don't understand the question.
Just "close" Firefox.

You understand that Firefox needs to run all those other instances?

I have attempted to close it. It is not closing properly. Sometimes programs do not close properly. That is the case.

Ghot · Jun 19, 2025

cokedude said:
I have attempted to close it. It is not closing properly. Sometimes programs do not close properly. That is the case.

Maybe start by opening a Terminal as Admin and running sfc /scannow
...and then running Dism /Online /Cleanup-Image /RestoreHealth

It sounds like there may be some other issues involved.
If the ONLY program that's hard to close is Firefox, then you may have a FF problem.
If there are other programs that also don't close easily, then you probably have a larger issue.

antspants · Jun 20, 2025

Did you try taskkill /IM firefox.exe /T /F
Or whatever the application exe
Not /f /t

Kill Process in Windows 11

This tutorial will show you how to kill a process (end task) in Windows 11. A process is an instance of an app or task that is being executed. Each process running in Windows is assigned a unique decimal number called the process ID, or PID. If you notice a running process is reducing your...

www.elevenforum.com

Morph000 · Jun 20, 2025

Grab Process Hacker:

Process Hacker

Download Process Hacker for free. View and manage processes, services and more with this powerful tool. Process Hacker is a free and open source process viewer. This multi-purpose tool will assist you with debugging, malware detection and system monitoring.

sourceforge.net

pepanee · Jun 20, 2025

If you're trying to stop Firefox from running in the background, try this:

AndreyT · Jun 20, 2025

cokedude said:
I have attempted to close it. It is not closing properly. Sometimes programs do not close properly. That is the case.

What is "not closing properly" supposed to mean? Provide a detailed description.

TairikuOkami · Jun 20, 2025

Morph000 said:
Grab Process Hacker:

Process Hacker was replaced by System Informer

You can see the parent process and restart it or terminate the whole tree.

KevTech · Jun 20, 2025

pepanee said:
If you're trying to stop Firefox from running in the background

That option is not in Firefox.
Must be a real old result as it is not called options anymore it is now called settings.

hdmi · Jun 21, 2025

Firefox has a built-in Process Manager. Press Shift+Esc to open it. It has an "Actions" column on the far right.

I wrote a simple command that can be run directly on the command line (not within a batch script, but you can modify it to make it work in a batch script) in an elevated command window. This command uses the WMIC tool and PsExec (from Sysinternals PsTools) to get SYSTEM privileges before it attempts to kill the parent process of Firefox—albeit that doesn't necessarily always help either. You'd have to make sure that the command can find the file PsExec.exe or else it definitely won't work. Also, I am assuming that you aren't running multiple instances of Firefox concurrently. (AFAIK no one here except only me ever does that anyway in the first place so, you should be good. lol) Here is the command:

@cmd /v:on /q /c "(for /f "usebackq" %B in (`for /f %A in ^('wmic process where name^^^="firefox.exe" get parentprocessid ^^^| more +1 ^^^| findstr /r /v "^^$" ^^^| sort /l C /uniq'^) do @wmic process where name^="firefox.exe" get processid ^| findstr %A`) do @set a=%B)&@psexec /s taskkill /f /pid !a!"

cokedude · Jul 9, 2025

Ghot said:
Maybe start by opening a Terminal as Admin and running sfc /scannow
...and then running Dism /Online /Cleanup-Image /RestoreHealth

It sounds like there may be some other issues involved.
If the ONLY program that's hard to close is Firefox, then you may have a FF problem.
If there are other programs that also don't close easily, then you probably have a larger issue.

I tried that. Thank you.

cokedude · Jul 9, 2025

antspants said:
Did you try taskkill /IM firefox.exe /T /F
Or whatever the application exe
Not /f /t

Kill Process in Windows 11

This tutorial will show you how to kill a process (end task) in Windows 11. A process is an instance of an app or task that is being executed. Each process running in Windows is assigned a unique decimal number called the process ID, or PID. If you notice a running process is reducing your...

www.elevenforum.com

I did that method with `taskkill` that you showed above and the other method with `taskkill` where I used the PID and neither method worked.

cokedude · Jul 9, 2025

Morph000 said:
Grab Process Hacker:

Process Hacker

Download Process Hacker for free. View and manage processes, services and more with this powerful tool. Process Hacker is a free and open source process viewer. This multi-purpose tool will assist you with debugging, malware detection and system monitoring.

sourceforge.net

Can you explain what to do with Process Hacker? I tried everything I could find with google and nothing seemed to help.

cokedude · Jul 9, 2025

pepanee said:
If you're trying to stop Firefox from running in the background, try this:

View attachment 137356

KevTech said:
That option is not in Firefox.
Must be a real old result as it is not called options anymore it is now called settings.

I think this is old like was was mentioned below. I also searched my settings for background and did not find it what way either.

cokedude · Jul 9, 2025

AndreyT said:
What is "not closing properly" supposed to mean? Provide a detailed description.

Using the x button in the top right corner that all programs have. clicking File, then clicking exit. Using the task manager. Using the command taskkill. taskkill /PID 16012 /F or taskkill /IM firefox.exe /T /F.

cokedude · Jul 9, 2025

TairikuOkami said:
Process Hacker was replaced by System Informer

You can see the parent process and restart it or terminate the whole tree.

Can you explain how to use that? What does Canary Builds mean on the download page? I will try to use this next time it happens.

cokedude · Jul 9, 2025

hdmi said:
Firefox has a built-in Process Manager. Press Shift+Esc to open it. It has an "Actions" column on the far right.

I wrote a simple command that can be run directly on the command line (not within a batch script, but you can modify it to make it work in a batch script) in an elevated command window. This command uses the WMIC tool and PsExec (from Sysinternals PsTools) to get SYSTEM privileges before it attempts to kill the parent process of Firefox—albeit that doesn't necessarily always help either. You'd have to make sure that the command can find the file PsExec.exe or else it definitely won't work. Also, I am assuming that you aren't running multiple instances of Firefox concurrently. (AFAIK no one here except only me ever does that anyway in the first place so, you should be good. lol) Here is the command:

@cmd /v:on /q /c "(for /f "usebackq" %B in (`for /f %A in ^('wmic process where name^^^="firefox.exe" get parentprocessid ^^^| more +1 ^^^| findstr /r /v "^^$" ^^^| sort /l C /uniq'^) do @wmic process where name^="firefox.exe" get processid ^| findstr %A`) do @set a=%B)&@psexec /s taskkill /f /pid !a!"

I do not see the actions column.

Where do I need to put PsExec.exe? I do sometimes run Firefox concurrently :).

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hdmi · Jul 10, 2025

cokedude said:
I do not see the actions column.

It's the narrow column on the far right. Its column header has a small cogwheel symbol.

cokedude said:
Where do I need to put PsExec.exe?

Place it In a folder e.g. C:\PsTools
In the command, substitute PsExec.exe with the correct filepath e.g. C:\PsTools\PsExec.exe

cokedude said:
I do sometimes run Firefox concurrently :).

With regular Firefox, any attempt to run a separate, additional, new instance of Firefox will typically give an error, "Another instance of Firefox is already running". You'd have to use the Portable edition of Firefox and configure it specifically for this purpose. I am not aware of any other way to achieve this so, I somehow doubt that it is what you are referring to. (Each time when I bring up this particular subject anywhere on the forum, no one replies to it or else it just gets misinterpreted again.)

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