Firefox or Iceweasel says it is already open

If firefox/iceweasel says it is already running, chances are you left it open and never logged off the machine. Be sure to logoff the machine completely when you are done to prevent this from happening.

Here is how to clear it:

  • Open a terminal/xterm or ssh to
  • type: cd ~/.mozilla/firefox
  • (yes, that is a period before mozilla)
  • type: cd *.default
  • type: rm lock
  • type: rm .parentlock
  • (yes that is a period before parentlock)