Firefox error - Firefox is already running, but is not responding......

User says firefox error:

"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"

There are two solutions to this problem:

Solution#1 - Command line:
1) Ask user to login and go to his home directory

2) Run following command:
bash-3.2$ find . -name ".parentlock" -exec ls -l '{}' \;
-rw-r--r-- 1 unixgeek group1 0 Jan 25 2007 ./.mozilla/default/7zeq10s5.slt/.parentlock
-rw-r--r-- 1 unixgeek group2 0 Mar 28 09:58 ./.mozilla/firefox/s6s5d3de.default/.parentlock

3) If user is sure that none of these files affect his/her currently running Firefox, ask him/her to delete those lock files. This will release all the locks Firefox application creates during a session.

4) In above example, user deleted both the files and voilà! It is working for user again!!! :)

Solution#2 - Using GUI:

1) Open profile manager using "firefox -P" command.



2) Click on "Create profile" to create a new profile.



3) Give a meaningful name to the profile (eg. profile1) and save/exit



4) Select the newly created profile and click on "Start Firefox"



Optionally, you can delete previously created profiles if you are sure that those profiles are NOT in use!!! Be careful while doing this.

Enjoy & give feedback if any of the above solution worked for you! :)