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I am trying to open Firefox browser in my system. But every time it is showing message that "firefox is already open but not responding. Please restart the system". Even after restarting the system it showing the same message, when i again try to open it.

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closed as off-topic by bain, Eric Carvalho, waltinator, Glutanimate, Radu Rădeanu Jul 12 '14 at 0:04

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Bug reports and problems specific to development version of Ubuntu should be reported on Launchpad so that developers can see, track and fix these issues." – bain, Eric Carvalho, Glutanimate, Radu Rădeanu
If this question can be reworded to fit the rules in the help center, please edit the question.

There might be a crashed firefox instance stuck. What is the output of ps aus | grep -i firefox in the Terminal? – mcantsin Jan 22 '14 at 13:24
Try killall firefox-bin on a terminal with sudo – AzkerM Jan 22 '14 at 13:26

Check the Firefox profile directory .mozilla/firefox/<profile> in your home directory and see if there is a file named .parentlock. Removing it should allow you to open Firefox again.

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I've had similar problem and,

killall firefox

fixed it.

But what's strange here is that you say even reboot didn't fix that!

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Firefox has a memory leak. Run htop and kill the process.

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