I am currently working on a theme for a client and now just got into a problem: When I want to set an image (also existing/already uploaded images don't work) the editor just not accept it and don't set it as the post thumbnail for the post.

Any help would be appreciated.

EDIT: Here is an screenshot for the case that somebody didn't know, what I am talking about:

enter image description here

It's like this before and after the "change". So what's going on there?

Normal file upload is working.


I figured out it was because of an script that was delivered with the Options Framework. There was a little piece of code in my functions.php which caused wrong javascript to be loaded.

When you are having the same problem, be sure to search for something like wp_enqueue_media(); or something of the following script, comment out and try to upload a thumbnail.

if( function_exists( 'wp_enqueue_media' ) ){
} else {

Thanks for all answers, though.


You need to add support for thumbnails in your theme. So, put this in your theme files:

function custom_theme_setup() { add_theme_support( $feature, $arguments ); } add_action( 'after_setup_theme', 'custom_theme_setup' );

This enables the thumbnail/feature image support for all post types in your current theme including normal posts and pages.

  • I already have this in my code. – Dominik Schmidt Jun 9 '15 at 13:40
  • 1
    If Dominik had this not enabled it would not even be shown in the editor. – Charles Jun 9 '15 at 13:47
  • Try activating/deactivating your plugins to see if that is the case if not try another theme and then set the thumbnail. This will narrow down you issue. – TalwinderSingh Jun 9 '15 at 13:48
  • @Charles Agreed – TalwinderSingh Jun 9 '15 at 13:49
  • @TalwinderSingh I just posted an answer, where I solved it by myself. Thanks, though! – Dominik Schmidt Jun 11 '15 at 10:28

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