When I try to run Firefox 3.6 or 4 beta I get a message saying:

Profile Missing
Your Firefox profile cannot be loaded.  It may be missing or inaccessible.

I have tried running the profile manger from the command line using:

/Applications/Firefox.app/Contents/MacOS/firefox-bin -ProfileManager

I get the same message in the popup, but I also get:

Error: Access was denied while trying to open files in your profile directory.

I have tried deleting Firefox and reinstalling it. I have also tried deleting anything related to Firefox or Mozilla in the ~/Library/Application Support directories, but nothing seems to help. In addition I have run the disk utility to fix any permissions issues.

If I create a new profile or run the command with sudo, it works. It seems that that Firefox is trying to put the profile somewhere it doesn’t have access to write, but I can’t figure out how to change this location or change the permissions. Any help would be greatly appreciated.

  • Is your account allowed to make administrative changes on the machine? Did you install Firefox as the same user as you're now trying to run it under?
    – Harv
    Jan 7 '11 at 3:56

A command was posted on the Firefox Help forum which works well to solve this problem:

Run this command in terminal from your home directory:

sudo chown -R `id -un`:`id -gn` ~

Give it a try. Your Mac will ask for your admin password which scared me a little. Firefox 4 works fine now on my MacBook Pro with OS X 10.6.7.


Cheng's response is a command that changes everything in your home directory to be owned by you. On my machine I only needed to do:

    sudo chown -R `id -un`:`id -gn` ~/Library/Caches

chown means 'change owner' and the '-R' means recursive

id is a command that returns your username with '-un' and your group name with '-gn'.


A low-rep user (Max2002) offered this suggestion:

I had a user that had Firefox 41.0 getting the error.  It turns out that the Caches folder within Library was not there.  There was a shortcut with the same name in its place.  I deleted the shortcut and Shazam! problem solved.  Running Firefox created the proper folder and the user could open Firefox!

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