Benedikt Winckler Benedikt Winckler - 1 year ago 92
PHP Question

Getting wordpress error: Cannot modify header information

I'm getting this error (I activated wp-debug) when I try to activate a theme or when I try to save a post:

Warning: Cannot modify header information - headers already sent by (output started at /mnt/webv/b3/13/56920413/htdocs/WordPress_02/wp-content/themes/BackpackFamily/functions.php:58) in /mnt/webv/b3/13/56920413/htdocs/WordPress_02/wp-admin/post.php on line 197

Warning: Cannot modify header information - headers already sent by (output started at /mnt/webv/b3/13/56920413/htdocs/WordPress_02/wp-content/themes/BackpackFamily/functions.php:58) in /mnt/webv/b3/13/56920413/htdocs/WordPress_02/wp-includes/pluggable.php on line 1171

That's the code of my functions.php, what did I do wrong?


// Navigation

if ( function_exists('register_nav_menus') ) {
'main-navi' => __( 'Hauptnavigation' )

// Thumbnails

if ( function_exists( 'add_theme_support' ) )
add_theme_support( 'post-thumbnails' );
set_post_thumbnail_size( 200, 200, true );

// Read more Link

function new_excerpt_more($more) {
global $post;
return ' … </br><a href="'. get_permalink($post->ID) . '">' . 'Mehr lesen &raquo;' . '</a>';
add_filter('excerpt_more', 'new_excerpt_more');

// Sidebar

function sl_sidebar() {
$args = array(
'id' => 'default_sidebar',
'name' => __( 'Sidebar Header', 'text_domain' ),
'description' => __( 'Sidebar Header', 'text_domain' ),
'before_title' => '<h3><a href="#">',
'after_title' => '</a></h3>',
'before_widget' => '',
'after_widget' => '',
register_sidebar( $args );

add_action( 'widgets_init', 'sl_sidebar' );

// Search Button

add_filter('get_search_form', 'new_search_button');
function new_search_button($text) {
$text = str_replace('value="Suche"', 'value="Suchen"', $text);
return $text;

Thanks for help!

Answer Source

Per your comment, the notice is being thrown on the last line of your functions.php file.

Which causes me to believe that you likely have stray line-feeds and /or spaces in your file somewhere outside (before, after, or between) your php tags (<?php and ?>)

Remove the closing php tag at the end ?> - it's the WordPress recommended code style now to omit the closing php tag.

Also, be sure there's no stray line feeds before the opening <?php tag.

This is a NOTICE, not really an error. If you had debug turned off, it would be a non-issue because notices would be silenced.
Kudos to you for testing your code with WP_DEBUG set to true. This is the only way to be sure your code runs without notices!

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