No Editor Icons, Empty Editor Boxes, Problems with Featured Image Upload in WordPress Back-end Problem

I had a problem on some WordPress site’s back-end  with empty meta boxes, no icons in wordpress text editor, featured image uploading lightbox didn’t worked etc. Thank God, there is a solution.

Add to wp-config.php on top:

 define('CONCATENATE_SCRIPTS', false);

This helps to avoid some JavaScript errors on WordPress backend. After addition my problems were magically cured.