

If you’ve tried everything above - including rebooting your computer - and you still see this message, it’s possible that your Firefox profile is still “locked.” Firefox is designed to ensure that only one copy of Firefox is using a profile at a single time. The “restart your computer” suggestion is for less-experienced users that may not want to deal with the Task Manager - restarting your computer works because it ends all the processes on your computer, including firefox.exe. If you encounter this error, you can always fix it without restarting your computer. Restarting your computer is the nuclear option and, quite frankly, isn’t a very good idea. No problem - just click the Processes tab. You can also right-click your taskbar and select Task Manager.įirefox won’t appear in the list of running applications because this list only shows applications with open windows.

First, open the Task Manager by pressing Ctrl+Shift+Escape. Luckily, ending Firefox in the Task Manager is simple. It may be frozen and using no system resources or it may be chewing up your available CPU time. While all Firefox windows may be closed, Firefox itself is still running in the background. If waiting a few seconds didn’t help, then Firefox has failed to quit properly. If you wait a few seconds and try launching Firefox again, you may find that it opens properly. This is because Firefox is still running in the background, doing housekeeping tasks and saving your data before quitting completely. If you’ve just closed all your Firefox windows and quickly tried to open a new one, you may see this message.
