Wordpress blog feed page error solution

Google chrome reports the following errors:

This page contains the following errors:

Error on line 4 at column 6: XML declaration allowed only at the start of the document
Below is a rendering of the page up to the first error.

 

The translation error is: the xml document declaration can only start with the document.

So I opened the chrome source file and read it. The strange thing is that there are three blank lines at the top of the document, and the xml document starts to appear in the fourth line. No wonder an error is reported.

Sort plug-ins
At first, I thought it was a problem with some newly installed plug-ins. As a result, I ran to the background and disabled plug-ins such as the plug-ins, such as the plug-ins without finding and speaking, and found that this empty line still exists. In my anger, I disabled the test by one plug-in, and later found that the problem still could not be solved.

Search Solution
Baidu has not found any content for a long time (this is because Baidu cannot find anything). After google, a similar problem was found in the wordpress Forum, the author reported 2nd rows, and I am the fourth row. According to the following statement, a fix-rss-feed plug-in provided by a great God has been downloaded and updated to version 3.1. With great hopes, we were disappointed after the installation. It doesn't seem like this.

Do it by yourself.
In desperation, I had to debug it step by step, first from index. start with php and test with echo 'test' to see if test appears above or below three empty rows. Echo 'test''s content is different until I keep track of the following code in wp-setting.php:

// Load the functions for the active theme, for both parent and child theme if applicable.
If (! Defined ('WP _ INSTALLING ') | 'WP-activate. Php' ===$ pagenow ){
If (TEMPLATEPATH! = STYLESHEETPATH & file_exists (STYLESHEETPATH. '/functions. Php '))
Include (STYLESHEETPATH. '/functions. Php ');
If (file_exists (TEMPLATEPATH. '/functions. Php '))
Include (TEMPLATEPATH. '/functions. php ');} if you know php, you can load the funcitons under the topic until the above part is loaded. php page, so we can conclude that the problem is here and go to the topic functions. in php, we can find such a piece of code:

Echo "</div> n ";
 } 
}?>
<? Php
// Remove unnecessary code from the header
Remove_action ('WP _ head', 'rsd _ link ');
Remove_action ('WP _ head', 'wlwmanifest _ link ');
Remove_action ('WP _ head', 'WP _ Generator ');
Remove_action ('WP _ head', 'start _ post_rel_link ');
The code I don't need to remove the header is removed from my blog that I love boiled fish. However, a php start character is added, and the gap between the code and the previous code is just three lines blank. The problem is here!

Summary
You can see from the wp-setting.php the theme functions in wordpress. the php hierarchy is still quite high, because topics may not be displayed on many pages, but some hooks and changes to non-display elements need to be supported by this file.