Why am I getting an error that Firefox is already running?

Owned by Marc Miller
May 08, 2018
1 min read

Problem

You are trying to open up Firefox, but Firefox says that it is already running.

Cause

This is due to Firefox not closing out properly (Due to a crash, Power Outage, network dropping while on a network account machine).

Firefox creates 'lock' files to make sure there is only one firefox application running.

Solution

To fix this, you will need to do the following based on which OS you are on:

If you are on one of the CSIL/Linux computers in Harold Frank Hall 1138/1140
  • Open up a terminal window (Using Terminal or Terminator)
  • Type the following command:

unlockff

or

/fs/eci/bin/unlockff

For Linux
  • Open up a terminal window (Using Terminal or Terminator)
  • In your home directory, there is a .mozilla directory, type 'cd .mozilla/firefox'
  • Type 'ls', you should see something like:

<a bunch of random characters>.default

  • Type 'cd <random characters>.default'
  • Type 'rm *lock' and 'rm .*lock' to remove the lock files.
For Mac
  • Open up a terminal windows (In the upper right hand corner with the magnifying glass, click on there and type 'terminal')
  • Type 'cd Library/Application\ Support/Firefox/Profiles'
  • Type 'ls', you should see something like:

<a bunch of random characters>.default

  • Type 'CD <random characters>.default'
  • Type 'rm *lock' and 'rm .*lock' to remove the lock files.


For Windows
  • Press 'Windows Key' and the 'R' key to pull up a Run window.
  • Type '%appdata%\Mozilla\Firefox\Profiles'
  • Double click on the folder ending with '.default' on it.
  • Delete the 'parent.lock' file you find.

You should be able to start Firefox with no issue.