This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

I get a error message trying to start Firefox

  • 4 replies
  • 1 has this problem
  • 2 views
  • Last reply by John99

more options

I have tried going back and restoring my computer so I can get Firefox working and still get a message stating "Failed to Read the Configuration File. Please contact your systems administrator". I have uninstalled Firefox and reloaded it with the most recent 23.0 edition with the same error message coming up when trying to start Firefox.

I have tried going back and restoring my computer so I can get Firefox working and still get a message stating "Failed to Read the Configuration File. Please contact your systems administrator". I have uninstalled Firefox and reloaded it with the most recent 23.0 edition with the same error message coming up when trying to start Firefox.

Chosen solution

You appear to have, or have had a none standard installation utilising a .cfg config file.

  1. Download a new copy of the Firefox installer
  2. Do a clean reinstall noting that includes deleting the Firefox program folder. That is essential in this case.
  3. Note NOT to delete the profile folder or use any options to remove personal information, because that will destroy bookmarks and passwords.

Full instructions



Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:

Note: You might want to print these steps or view them in another browser.

  1. Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
  2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
  3. Delete the Firefox installation folder, which is located in one of these locations, by default:
    • Windows:
      • C:\Program Files\Mozilla Firefox
      • C:\Program Files (x86)\Mozilla Firefox
    • Mac: Delete Firefox from the Applications folder.
    • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
  4. Now, go ahead and reinstall Firefox:
    1. Double-click the downloaded installation file and go through the steps of the installation wizard.
    2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.
Read this answer in context 👍 3

All Replies (4)

more options

hello happybradboating, please try if you can get firefox working again like this: press the windows-key + R and open %appdata%\Mozilla\Firefox\. a windows explorer window should open up - if you find a file named profiles.ini in there, try renaming it to something like oldprofiles.ini .
also right click on a blank space somewhere in the folder and make sure in the properties that neither the folder or any of the subdirectories are write-protected...

more options

Chosen Solution

You appear to have, or have had a none standard installation utilising a .cfg config file.

  1. Download a new copy of the Firefox installer
  2. Do a clean reinstall noting that includes deleting the Firefox program folder. That is essential in this case.
  3. Note NOT to delete the profile folder or use any options to remove personal information, because that will destroy bookmarks and passwords.

Full instructions



Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:

Note: You might want to print these steps or view them in another browser.

  1. Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
  2. After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
  3. Delete the Firefox installation folder, which is located in one of these locations, by default:
    • Windows:
      • C:\Program Files\Mozilla Firefox
      • C:\Program Files (x86)\Mozilla Firefox
    • Mac: Delete Firefox from the Applications folder.
    • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
  4. Now, go ahead and reinstall Firefox:
    1. Double-click the downloaded installation file and go through the steps of the installation wizard.
    2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

Modified by John99

more options

I went with deleting all mozilla directories under programs then reinstalled Firefox. It runs good and I will add my user names and pass words as needed. Thanks Brad

more options

Thanks for postingback. Glad it is working again.

As long as you followed the instructions and did not delete the profile you should not have lost paswords and user names. They are stored in the profile and not in the programs folder.