Dtyjlui

I got the same case, and I tried to change permission of mozilla cache and it worked:

root mode

sudo -s

chown -hR $USER:$USER ~/.cache/mozilla

but after I changed, there's pop-up suggested me when I opened firefox to create a new profile. I just want to use an older profile. So I changed the permission of old profile too into my user!

chown $USER:$USER ~/.mozilla/firefox/profiles.ini

dont forget to make a sure the file permission is changed :)

Removed profile file, changed permissions of profile folder, etc. None of them worked. Finally, changing ownership recursively on ~/.cache worked :

sudo chown -R $USER:$USER ~/.cache/

After all other solution this little line saved my day:

sudo chmod -R 777 .mozilla/

Try deleting the current profile. That will force Firefox to create a new profile. Profile folders are located here:

~/.mozilla/firefox/<profile folder> 

The .mozilla folder is a hidden folder. Make sure that you check show hidden files in your file manager (Browser).

Had a similar issue. Had to delete the profiles.ini file in ~/.mozilla/firefox/. Tried all kinds of permissions solutions to no avail. Once profiles.ini was deleted, firefox created a new profile.

I just encountered this in 14.04 after an attempt to move files from my previous install failed. I am no expert, but this worked:
Edited profiles.ini file in ~/.mozilla/firefox/
commented out (using ; below)

;Path=[this.is.a.hash].default

Created a new path line so that the hash matched the [this.is.a.hash].default folder name in ~/.mozilla/firefox/

Maybe I could have renamed the folder to match the name in profiles.ini, but easier to trace back the problem knowing I could delete the new and uncomment the old Path= from within profiles.ini.

Fortunately for me, I installed 14.04 on a new SSD and kept the old 12.x release. Now I'll try what I should have done in the first place - a proper Firefox profile backup/move from the old installation.

Copy your profile-folder to /home/USERNAME/.mozilla/firefox and run firefox -Profilemanager or firefox -P in terminal, create new profile and select your old profile's folder.
Starting the Profile Manager

If you linked your ~/.cache directory to an external drive (something similar to this guide on how to run Firefox off your RAM), try removing your existing link and creating again that directory.

I just ran into this error because a few months earlier I went into a hacking fit in a VM and linked that folder into an USB drive to cut down on HDD activity, and then I migrated my VM to another host computer and removed the drive where that folder was located, and now that the link was broken Firefox wouldn't start and gave me this error message. I recreated this directory, and now Firefox starts fine.

Following steps worked for me.

1.Kill all currently running process

killall firefox

killall thunderbird

2.Remove the cache Files

Note: Backup them before removing.



$ rm -rf ~/.mozilla/

$ rm -rf ~/.cache/mozilla/

3.Change the ownership of following folders

$ sudo chown -R $USER ~/.cache/.mozilla/

$ sudo chown -R $USER ~/.mozilla/

** if the above step NOT successful, Then try following **

$ sudo chown -R $USER:$USER ~/.cache/.mozilla/

$ sudo chown -R $USER:$USER ~/.mozilla/

** if the above step NOT successful, Then try following **

$ sudo chmod -R 777 ~/.cache/.mozilla/

$ sudo chmod -R 777 ~/.mozilla/

4.If all above steps NOT successful, Then change entire cache folder permission

$ sudo chown -R $USER ~/.cache

$ sudo chown -R $USER:$USER ~/.cache

$ sudo chmod -R 777 ~/.cache/