Firefox crashes on Windows 10 machine

Hi Before uninstalling and reinstalling Firefox, there are a few things worth trying, since your Firefox profile may contain your bookmarks, passwords, history, and other data.

The “Firefox is already running” message usually means Firefox did not shut down cleanly and a Firefox process is still running in the background.

1. Press Ctrl + Shift + Esc to open Windows Task Manager. 2. Look for Firefox or firefox.exe in the Processes list. 3. If you find it, select it and choose End Task. 4. Start Firefox again and see if it responds normally.

If Firefox still becomes unresponsive, try starting it in Troubleshoot Mode: hold Shift while starting Firefox, or use ☰ → Help → Troubleshoot Mode… if Firefox stays open long enough.

If it works in Troubleshoot Mode, an extension or hardware-acceleration setting is a likely cause.

I would avoid uninstalling Firefox as the first step. If we do need to reinstall it, we can first make sure your Firefox profile and important data are backed up.

Brought up Task Manager before clicking on Firefox and you were right, Firefox is already running. Clicked "End Task" and then brought up Firefox normally. Thanks for that. I checked the Firefox settings and I do not have the block checked to bring up Firefox at boot up and yet it is partially coming up. It doesn't come up all the way though. As it is, right now, I have to bring up Task manager and end task before bringing up Firefox. I have Firefox on my Windows 11 machine and am not having that problem. Any suggestions greatly appreciated. -JJM

Hi,

I believe that's an intended experiment that started with v154. You should be able to disable this behavior for Firefox from the Task Manager, the Startup section (right-click the Firefox entry and select Disable).

It started on my machine (Windows 10) before 154 came out. I was hoping 154 would fix it but it didn't. If I disable the start-up in task manager, won't that prevent Firefox from coming up at all?

Weird... Either way, startup only refers to programs opening automatically when you boot your device. It doesn't affect manual opening at all.

Okay, I'll give it a try. Thanks.