add_filter( 'pre_handle_404', function($param1, $param2) {

    $post_id = url_to_postid("http://".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI']);
    if (!empty($post_id)) {

	    $td_post_theme_settings = td_util::get_post_meta_array( $post_id, 'td_post_theme_settings' );
        // standard smartlist
	    if ( is_array( $td_post_theme_settings ) && array_key_exists( 'smart_list_template', $td_post_theme_settings ) ) {
            return true;
	    } elseif ( !empty ($td_post_theme_settings['td_post_template']) && td_global::is_tdb_registered() && td_global::is_tdb_template($td_post_theme_settings['td_post_template'], true) ) {  // cloud template smartlist
                $td_template_id = td_global::tdb_get_template_id($td_post_theme_settings['td_post_template']);
                $td_template_content = get_post_field('post_content', $td_template_id);
                $is_tdb_smartlist = tdb_util::get_shortcode($td_template_content, 'tdb_single_smartlist');

            if ( $is_tdb_smartlist ) {
                return true;
            }
        }
    }
    return $param1;
}, 10, 2);