My wordpress feed started giving me an error of:

“error on line 2 at column 6: XML declaration allowed only at the start of the document”

This was due to a white space at the beginning of the feed. It was actually a quick an easy fix. The Fix RSS Feed plugin did NOT work for me.

Step 1) Download this white space fix: http://wejn.org/stuff/wejnswpwhitespacefix.php

Step 2) Edit your index.php to include this new file. It’ll look like this:

include("wejnswpwhitespacefix.php");
define('WP_USE_THEMES', true);
require('./wp-blog-header.php');

Step 3) Check this code modification every time you update wordpress!

Many thanks to: The WordPress Consultant