Web browser doesn't open (Failed to read the configuration file)

The "Failed to read the configuration file" error is caused by a problem with Firefox program files. The solution is to remove the Firefox browser and then reinstall it:

1. Uninstall Firefox (See the don't know how to uninstall a program / an application for details)
   
   
2. Delete the Firefox installation directory, found in one of these locations by default:
   • C:\Program Files\Mozilla Firefox
   • C:\Program Files (x86)\Mozilla Firefox
     
     
3. Use another browser to download Mozilla Firefox from the official website
   
   

Note:  This solution also applies if you see the message "XULRunner - Error: Platform version is not compatible with minVersion "" (depends on the Firefox's version number), after a software update

This will not remove your passwords, bookmarks or other user data and settings, as they are stored in a different folder.

Use a utility such as Advanced Uninstaller PRO to uninstall programs from your computer to delete all the files (even the installation files) related to them in all the directories.

Every new release of a web browser includes a number of fixes for crashes that were reported by people. If your web browser doesn't open or crashes very often, check for updates by visiting the browser's official website and downloading and installing the latest version (if available).

Note: Don't download browsers from websites other than the browser's official website because they might have been modified to harm you and you might end up having your passwords (or even credit card numbers) stolen.