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how do we make firefox read the configuration file

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! Failure to read the configuration file. Please contact your system administrator.

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Step:1) Created a file name like "local-settings.js" in -- /usr/lib/firefox/defaults/pref --- Pasted this line -- pref("general.config.filename", "mozilla.cfg"); --- in "local-settings.js" Step :2) Created a file name like "mozilla.cfg" in -- /usr/lib/firefox --- And copy and paste the below line in this "mozilla.cfg" file.

defaultPref(); // set new default value pref(); // set pref, but allow changes in current session lockPref(); // lock pref, disallow changes

Troubleshooting steps: The steps look fine to me (byte shifting is no longer required).

  1. Do any of the prefs have a locked setting in you click the Status header on the about:config page?
  2. Do you see the general.config.filename pref with value mozilla.cfg on the about:config page?
  3. Are you sure that you are starting this version of Firefox?
  4. Do you get an error message when the mozilla.cfg file is absent?
  5. You will first have to check for errors with the local-setting.js file
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If you get this error that means that there is a local-settings.js file present, but there is a problem with the mozilla.cfg file.

Can you post the content of the mozilla.cfg file?

Note that the mozila.cfg file is run as JavaScript with full chrome privileges and any error in the file will throw an exception.

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If you didn't create the local-settings.js file and the mozilla.cfg file yourself then you will have to remove both files or at least the local-settings.js file in the defaults/pref folder where also the channel-prefs.js file is located.

See also:

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I am not a computer nerd and would just like Firefox to work!

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Hi frustratedx10

Do you see an alert that shows this error message?


Do a clean reinstall and delete the Firefox program folder before (re)installing a fresh copy of the current Firefox release.

If possible uninstall your current Firefox version to cleanup the Windows registry and settings in security software.

  • Do NOT remove "personal data" when you uninstall your current Firefox version, because this will remove all profile folders and you lose personal data like bookmarks and passwords including data in profiles created by other Firefox versions.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

  • (32 bit Windows) "C:\Program Files\Mozilla Firefox\"
  • (64 bit Windows) "C:\Program Files (x86)\Mozilla Firefox\"

Your bookmarks and other personal data are stored in the Firefox profile folder and won't be affected by an uninstall and (re)install, but make sure NOT to remove personal data when you uninstall Firefox as that will remove all Firefox profile folders and you lose your personal data.

If you keep having problems then also create a new profile.

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Deleting the Mozilla folder did the trick, I thought when I uninstalled firefox that it would have deleted it. Now I know. Thank you very much, you have no idea how much I've missed my Firefox the last couple weeks! It is great to have it back!