Ticket #32464: 32464.2.patch

src/wp-includes/nav-menu-template.php

@@ -338 +338 @@
                         $show_container = true;
                         $class = $args->container_class ? ' class="' . esc_attr( $args->container_class ) . '"' : ' class="menu-'. $menu->slug .'-container"';
                         $id = $args->container_id ? ' id="' . esc_attr( $args->container_id ) . '"' : '';
-                        $nav_menu .= '<'. $args->container . $id . $class . '>';
+                        //If 'container' = true instead of an element name, then use default of 'div'
+                        $nav_menu .= '<'. (is_bool( $args->container ) ? 'div' : $args->container) . $id . $class . '>';
                 }
         }