All Products Community Forum

I have tried all suggestions from the "Firefox is already running..." page but could not fix the problem.

I don't know if this is a problem, but I have several profile folders (see image). The top one is empty, but two folders below that one, are 2 GB or more in size.

Should I delete some or any of them?

Firefox cannot start because Mozilla process is already running and I cannot stop it.

I tried to restart my PC but no success. I reinstalled Mozilla/Firefox but again error message appears:

"Firefox is already running, but is not responding. The old Firefox process must be closed to open a new window."

My iMac automatically updated to the latest version of Firefox and now Firefox won't open at all. I keep getting an error message about installing a helper tool. I tried both installing the Helper Tool and canceling (see attached image) with no success. Please advise.

Thanks! Carol Boehler cboehler2@unl.edu

I reinstalled it many times. I also force-quit the process in Task Manager. Basically, I did everything Google told me to do. But everything was the same. It says: Firefox is already running but is not responding. To open a new window, the running Firefox process must be terminated. please help

Nachdem ich Mozilla VPN heruntergeladen und installiert hatte, stürzte mein Firefox Browser regelmäßig beim Start ab, so das ich Mozilla VPN wieder deinstallieren musste um überhaupt wieder in Firefox zu gelangen ?????

Gruss Robert

After the latest version was updated, Version 149.00.7, on my laptop, on 27 March 2026, the browser closed midway while I was working, and now I can no longer access Firefox.

When I click on the Icon to access I keep getting the following error message as per the attachment:

I have uninstalled Firefox and re-installed it THREE TIMES already', but I still get the same error as before, as per the screen print provided.

I have even tried to install Firefox with custom settings, but then in order to proceed with the installation the ONLY button to proceed was the "UPGRADE" option.

I am at my wits end because this is totally unacceptable and the updated version obviously DOES NOT WORK!!!

Your urgent attention and prompt action in sorting this out will be appreciated, thanks.

Hettie

Could not open Firefox App on my Android phone last night. Kept geting the message "Firefox keeps stopping", before the App had even opened.

Tried clearing cache. Tried Force Stop Tried retarting phone. Tried uninstalling Firefox app and Installing fresh Firefox App.

Nothing has worked. Still getting "Firefox keeps stopping", before the App has even opened.

Android 10 QPWS30.61-21-18-7 Firefox Version 148.0.2

I apprciate it's an old phone but the App was fine until yesterday?

Help?!

Version: Mozilla Firefox for Linux 149.0 Device: Termux v. 0.119.0-beta.3 Output: IceWM 4.0.0 + XServer XSDL v. 1.20.53 Log: ``` $ firefox --no-remote --alsa-output-device=default --display=:0 console.error: "Warning: unrecognized command line flag" "-alsa-output-device" Exiting due to channel error. Exiting due to channel error. Crash Annotation GraphicsCriticalError: |[C0] [GFX1-]: CompositorBridgeChild receives IPC close with reason=AbnormalShutdown (t=1.68679) Segmentation fault firefox --no-remote --alsa-output-device=default --display=:0 $ echo $? 130 ``` Reinstall tried. Refresh tried. Malware checked - none. Trouble Shooting mode log: ``` $ firefox --safe-mode Exiting due to channel error. Exiting due to channel error. Exiting due to channel error. Exiting due to channel error. Exiting due to channel error. Segmentation fault firefox --safe-mode $ echo $? 139 ``` Without tags start ``` $ firefox Exiting due to channel error. Exiting due to channel error. Bus error firefox $ echo $? 135 ``` Sometimes it can be started but not stable Maybe the problem is: problem with about:sessionrestore, everytime I open it, I can see about:sessionrestore page for short, and when it can start up (sometimes in troubleshooting mode), after choose a option, browser crash, and if I open another tag and close it, browser runs as normal.