When I launch Start Tor Browser.exe it indicates that the circuit is established but then immediately gives the following error message:

Firefox is already running, but not responding. To open a new window, you must first close the existing Firefox process, or restart your system.

This happens even though Firefox is not running. How can I resolve this issue?

  • This is also happening to me - I have checked the task manager and there is no "firefox.exe" process running. – Tahir Hassan Apr 15 '14 at 14:03

Whenever I've got that message, it's been because a Firefox process actually was running, even though there was no Firefox window. Since it sounds like you're running Windows, have you tried Ctrl-Alt-Del to open the system manager and looked for a Firefox process? If you find one, try killing it.

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  • 1
    Firefox doesn't always shut down cleanly. If you can consistently reproduce this, perhaps you should file a bug? – flamsmark Dec 10 '13 at 10:54

I had a similar problem, though the firefox process was closed. Additionally if I tried to open TorBrowser parallel to normal Firefox it just opened another (normal) Firefox window. I had installed TorBrowser on C:\Program Files\Tor Browser. Try to extract the Tor Browser Bundle on another partition, on an external harddrive or an USB-stick. This worked in my case.

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  • Firefox uses interprocess communication to control the running instance. This mechanism should not depend on where is the firefox executable file. I guess that there must be something different. – pabouk Jan 31 '14 at 10:19
  • I have installed it in my D:\ drive and it seems to be working. Thanks. – Tahir Hassan Apr 15 '14 at 14:06
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    The error message is misleading, it hasn't to do with Firefox running. Because it needs write access to its own folder, Tor browser needs admin privileges when it's installed in Program Files folder. Either install the Tor bundle outside a system folder (such as c:\tools) or run it as Administrator (bad idea). – Martin Hansen May 15 '14 at 15:25

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