Plugin Breaking Wordpress Login

Question

Two issues with this plugin, please help...

1 My plugin is breaking my /wp-admin to where all I get is a white screen instead of forwarding to the login screen, which is also broken when this is enabled. The rest of the site works.

2 Another problem with my plugin is that I can't get it to echo back the files in that directory. There are two files in there styles.css and new.css. I've used this method to display files in a folder before but I can't get it to work here.

<?php
 /*
Plugin Name: Call Custom CSS
Description: Call custom CSS files to your theme while still being to recieve theme development updates
Version: 1.1.0
Author: Michele Narup
Author URI: http://michelenarup.com
*/

function addcss(){
$directory = get_site_url() . "/wp-content/css/";
$stylesheets = glob($directory . "*.css");

wp_enqueue_style('styles' , get_site_url(). '/wp-content/css/style.css');
//echo $directory;
    foreach($stylesheets as $stylesheet)
    { 
    echo "<link rel='stylesheet'";
    echo $stylesheet;
    echo "type='text/css' media='all' />";
    }
}
add_action('wp_head', 'addcss');

 ?>

As per a discussion in the comments below I changed the function to now read:

 /*
Plugin Name: Call Custom CSS
Description: Call custom CSS files to your theme while still being to receive theme development updates
Version: 1.1.0
Author: Michele Narup
Author URI: http://michelenarup.com
*/


function load_my_style () {
wp_register_style('customstyle', get_site_url() . '/wp-content/css/style.css');
wp_enqueue_style('customstyle');
}

add_action('wp_enqueue_scripts', 'load_my_style');

This works but does not fix the white screen problem. /wp-admin is still not rendering anything at all on the page or page source. Also note, problem #2 is now irrelevant based on the new function, I will revisit that later. For now I'm focusing on getting the login screen to work.

Answer 1

The error "Cannot modify header information, headers already sent" often occurs when you have white space before the opening php tag, or after the closing php tag.