Ticket #13998: 13998.2.patch

src/wp-includes/post-template.php

@@ -1289 +1289 @@
                 if ( isset( $args['fallback_cb'] ) &&
                         'wp_page_menu' === $args['fallback_cb'] &&
                         'ul' !== $container ) {
-                        $args['before'] = '<ul>';
+
+                        // Apply the menu_class parameter to the <ul> to align with wp_nav_menu().
+                        $class = ! empty( $args['menu_class'] ) ? ' class="' . esc_attr( $args['menu_class'] ) . '"' : '';
+
+                        $args['before'] = "<ul{$class}>";
                         $args['after'] = '</ul>';
                 }