Fixing "Firefox is already running" error in Linux

If you are on Linux and you get the following error when trying to start Firefox, read on for a solution:

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.

This error usually is not solvable with killing the Firefox process, since you won't find one in the list of the current processes.

So how do we get around it?

First, you need to go to your profile directory.

• cd  ~/.mozilla/firefox/[your_profile]

Then delete the following two files :

• rm lock
• rm .parentlock

You should be able to open Firefox now.

If you have this problem occurring often like me, put the above command in a shell script for more convenience.