Problem with ‘post__not_in’
You are trying to supply an array as part of the string query parameter. You could instead just supply the arguments list as an array like this: $newQuery = new WP_Query( array( ‘posts_per_page’ => 5, ‘orderby’ => ‘rand’, ‘cat’ => $cats[0]->term_id, ‘post__not_in’ => array($exclude_post) ) );