XML RSS new line problem.

Somewhere along the line a new line was being placed before the XML declaration in the feeds. This caused an error to display in Firefox and other browsers instead of the feed.

I searched high and low to find where it was coming from. Disabled all me plugins, removed blank lines from code etc. To no avail. Then I noticed that the error was happening on a Mac but not in Windows. So it had to do with something about how Windows, Mac, and Linux/Unix deal with carriage returns and new line characters. I didn’t think I’d ever find the ghost new line (or return) so I tried to find a way to delete it.

Here is the hack/fix. What I’ve done is start an output buffer, and then clear it before the XML/RSS template is loaded.

In the index.php file put ob_start() like this:

<php
ob_start();

In wp-includes/functions.php add ob_end_clean() to the beginning functions that load the feed templates.

/**
 * Load the RDF RSS 0.91 Feed template.
 *
 * @since 2.1.0
 */
function do_feed_rdf() {
    ob_end_clean();
	load_template( ABSPATH . WPINC . '/feed-rdf.php' );
}

/**
 * Load the RSS 1.0 Feed Template
 *
 * @since 2.1.0
 */
function do_feed_rss() {
    ob_end_clean();
	load_template( ABSPATH . WPINC . '/feed-rss.php' );
}

/**
 * Load either the RSS2 comment feed or the RSS2 posts feed.
 *
 * @since 2.1.0
 *
 * @param bool $for_comments True for the comment feed, false for normal feed.
 */
function do_feed_rss2( $for_comments ) {
    ob_end_clean();
	if ( $for_comments )
		load_template( ABSPATH . WPINC . '/feed-rss2-comments.php' );
	else
		load_template( ABSPATH . WPINC . '/feed-rss2.php' );
}

/**
 * Load either Atom comment feed or Atom posts feed.
 *
 * @since 2.1.0
 *
 * @param bool $for_comments True for the comment feed, false for normal feed.
 */
function do_feed_atom( $for_comments ) {
    ob_end_clean();
	if ($for_comments)
		load_template( ABSPATH . WPINC . '/feed-atom-comments.php');
	else
		load_template( ABSPATH . WPINC . '/feed-atom.php' );
}

This worked without the change to the index.php file, but I don’t think it should have.

I tried to accomplish this with a plugin, but it wouldn’t work. since this is editing WordPress core files, these changes will need to be made again after an upgrade if the problem persists with the new version.