Here we go to understand a solution to solve the white space error that cause corrupt output for the wordpress rss feed or any other rss feed or www document that need the very first character of the output is the character < of the xml document declaration and not white spaces (or something else: the str_replace() function can be modified to fit any needs).

Read the easy tricky way by axew3 to solve commons wordpress rss feed error problems in this page:

http://www.w3it.org/blog/wordpress-feed-output-error-solution-how-to/