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Failed to read the configuration file. Fresh install on windows 7

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  • 13 have this problem
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  • Last reply by FredMcD

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I have just downloaded and installed firefox on my windows 7 computer. No errors on the install. When I try to launch Firefox I get this dialog box. Configuration Error - Failed to read the configuration file. Please contact your system

administrator.

Chosen solution

Note that you need to delete the Firefox program folder to do a clean reinstall to remove the file that tries to access the mozilla.cfg file that is probably not present.

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I found an archived response that said to remove your current Firefox (Not the profiles), then re-install the current version.

Download Firefox Full Installer For All languages And Systems {web link} Save the file.

Uninstall Firefox from your computer {web link}

After, reboot the computer. Then run the full installer.

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Check for the presence of a mozilla.cfg file in the Firefox program folder to initialize some prefs.

This also involves the presence of a .js (JScript) file, probably in "defaults\pref" folder, that specifies to process this mozilla.cfg file.

If you have .js files apart from the channel-prefs.js file, that sets app.update.channel, in the defaults\pref folder then open this file in an editor like Notepad and please post its content. Also please post the content of the mozilla.cfg file.

There shouldn't be a mozilla.fcg file present unless you've created it yourself to initialize some prefs.

If you have this mozilla.cfg file then best is to do a clean reinstall and delete the Firefox program folder before reinstalling a fresh copy of Firefox.

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FredMcD I have tried to uninstall and then do a fresh install and got the same result. thank you for the reply.

Cor-el I do not have a mozilla.cfg on the system. And not quite knowing what to look for I do have quite a number of .js files and they reside in /Desktop/Old Firefox Data/om9pictp.default/ Prefs.js; sessionstore.js ;user.js; and about 30 more .js files. I am wondering if I am looking in the right place? thanks

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You need to look in the Firefox program folder.

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

What files do you see in the \defaults\pref folder in the Firefox program folder?

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Chosen Solution

Note that you need to delete the Firefox program folder to do a clean reinstall to remove the file that tries to access the mozilla.cfg file that is probably not present.

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Cor-el and FredMcD

I feel a littled embarrassed because somewhere I did not follow your instructions. This time I uninstalled, deleted the firefox folder, rebooted, did a fresh install and now it works. Thank you very much for your help I really appreciate it.

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Good to hear, Safe surfing.