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If Firefox is frozen, end its process in your operating system’s process manager: use Task Manager on Windows, Activity Monitor on macOS, or System Monitor or equivalent process controls on Linux. This abruptly closes Firefox and can lose unsaved work. If Firefox still responds, quit it normally first.
Try a normal quit first
If Firefox still responds to clicks and keystrokes, use its menu to exit: choose Exit on Windows, Quit Firefox on macOS, or Quit on Linux. A normal quit gives Firefox a chance to close cleanly. Mozilla describes a hang as Firefox stopping its response to clicks and keystrokes and appearing to do nothing; for that situation, use the steps for your operating system below. Mozilla Support: Firefox hangs or is not responding.
Force close Firefox on your computer
Windows
- Open Task Manager by pressing Ctrl+Shift+Esc. Alternatively, right-click the taskbar and open Task Manager.
- Find Firefox in the list of apps or processes. If it is listed under a group, expand that group if needed.
- Select Firefox and choose End task. In Windows 11, Mozilla notes that this action closes all Firefox windows without another prompt.
Because the process is ended abruptly, unsaved work may be lost. Mozilla Support: “Firefox is already running but is not responding”.
macOS
- Open Activity Monitor.
- Look for the Firefox process. Mozilla’s troubleshooting guide identifies the process name firefox-bin.
- Select the process and use Activity Monitor’s process controls to quit it. If it does not quit, use the available force-quit option.
Process labels and interface details can vary. Mozilla identifies Activity Monitor as the relevant tool but does not specify a more detailed Mac menu path in its troubleshooting guide. Mozilla Support Contributors Help: Firefox Support troubleshooting guide.
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Linux
- Open your desktop environment’s System Monitor or equivalent process manager.
- Find a Firefox process, commonly labeled firefox or firefox-bin.
- Select it and choose the option to end or kill the process.
Mozilla gives Ubuntu’s System Monitor as an example; process names and menu labels vary by Linux distribution. If your desktop does not provide a process monitor, consult your distribution’s documentation for its process-control method rather than guessing at a command. Mozilla Support’s locked-profile troubleshooting article.
If Firefox still appears to be running
Closing every visible Firefox window does not always end the background process. If a Firefox process remains, it can prevent a new launch and trigger an “already running” or “not responding” message. Reopen the process manager, end any remaining Firefox processes, and try launching Firefox again. Restarting the computer is another option if you cannot clear the remaining process. Mozilla Support explains that Firefox may remain in memory after its windows close.
If Firefox reports that its profile is locked even after the process is gone, that is a separate startup problem. Mozilla describes removing a leftover profile lock file as a follow-up for that specific error; do not delete profile data as a general force-close step. See Mozilla’s profile-lock troubleshooting guidance.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Force closing is not a fix for recurring hangs
Ending Firefox can get you out of a freeze, but it does not explain or repair why Firefox stopped responding. Mozilla’s hang troubleshooting guidance, listed as updated August 8, 2026, covers follow-up checks such as hardware acceleration and other issue-specific causes: Firefox hangs or is not responding – How to fix.
Do these 3 things before closing this tab:
1Fix the driver behind crashes, sound loss and screen glitches2Repair Windows errors before they cause bigger problems3Scan for outdated or missing drivers - takes under a minuteAn unexpected disappearance is different from a hang: if Firefox closes or quits on its own, use Mozilla’s crash troubleshooting steps rather than treating it as an unresponsive process. Mozilla Support: Troubleshoot Firefox crashes.
These instructions cover desktop operating systems. The cited Mozilla guidance does not establish force-close steps for Firefox on Android or iOS.
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