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Firefox will not open. It says 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. I have restarted my computer multiple times

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Firefox will not open. It says 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. I have restarted my computer multiple times

Help please

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Shooting Star Contributor

Re: Firefox will not open. It says 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. I have restarted my computer multiple times

Sounds like Firefox is "hanging at exit". That problem is frequently caused by an Extension or a Plugin. Read all of the following articles.

NOTE: Establish a habit of exiting/closing Firefox with Firefox button > Exit or File > Exit to allow an orderly shutdown of Firefox and closing of all of the files that Firefox has open.


  1. Stop the Firefox process:
  2. Why Firefox may hang:
  3. Use Firefox Safe Mode to find a problem with an Extension or Plugin:


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