Ever got this message before and wondered WTF is going on? I did. Was working on a site on specified development URL only my client had access to. Implemented RSSfeeds for all the blog categories with the following in WordPress:

[php] wp_list_categories(‘feed_image=http://www.yoururl.com/wp-content/themes/simplo/images/feed.png&feed=XML Feed&optioncount=1&children=0’);?>[/php]

Once approved, I copied it over to their live site. Only to be met with the following when testing:

XML Parsing Error: XML or text declaration not at start of entity

What’s the problem? Turns out it’s related to a situation that has plagued me before – white space before or after the ‘<?’ in your themes function.php file.