Firefox is already running but is not responding

Posted December 26th, 2008 in Applications

If you ever shut down Firefox and try to start it up again directly afterwards it might display the rather alarming error message "Firefox is already running, but is not responding..." and doesn't start up. This post looks at the error message and what to do.

The full error message is "Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system" and is shown in the screenshow below running Firefox 3.0 on Windows Vista.

This is a pretty alarming sounding error message, but all it means is that Firefox hasn't yet completely shut down yet and done whatserver state or preference saving is required, so it won't let you start it up again yet.

Just wait a few more seconds and then try again and it should start up again OK.