Add the code into your function.pgp
// Deregister editor-expand as it breaks CKEditor integration
function custom_deregister_editor_expand() {
wp_deregister_script(‘editor-expand’);
}
add_action( ‘admin_init’, ‘custom_deregister_editor_expand’ );
I found the answer here: https://wordpress.org/support/topic/not-compatible-with-wordpress-40-41?replies=7
Thanks Alex.
