AUS: Update XML File Malformed (200) Firefox Update Error

Recently one my blog reader was angry that I posted something related to Microsoft Windows ;). Why shouldn't I write about that it?. There whole lot of free software that runs on it, programming languages, Office tools, editors you name it. Mozilla Firefox is perhaps the most common one. This is post discusses this odd Firefox error message which is triggered when the browser try to check for latest updates.

This AUS Update XML File Malformed 200 error traps many issues, the simplest being unable to access the Internet. So, most of the time you can safely ignore this warning.

Test Case

1. File>Work Offline
2. Help>Check for Updates

Gnu/Linux users running firefox installed from the distribution package would find that Check for Updates feature is disabled.