diff --git src/wp-includes/customize/class-wp-customize-nav-menu-item-setting.php src/wp-includes/customize/class-wp-customize-nav-menu-item-setting.php
index 11b5cd6..c970f2f 100644
--- src/wp-includes/customize/class-wp-customize-nav-menu-item-setting.php
+++ src/wp-includes/customize/class-wp-customize-nav-menu-item-setting.php
@@ -722,7 +722,13 @@ class WP_Customize_Nav_Menu_Item_Setting extends WP_Customize_Setting {
 		$menu_item_value['attr_title'] = wp_unslash( apply_filters( 'excerpt_save_pre', wp_slash( $menu_item_value['attr_title'] ) ) );
 		$menu_item_value['description'] = wp_unslash( apply_filters( 'content_save_pre', wp_slash( $menu_item_value['description'] ) ) );
 
-		$menu_item_value['url'] = esc_url_raw( $menu_item_value['url'] );
+		if( '' !== $menu_item_value['url'] ) {
+			$menu_item_value['url'] = esc_url_raw( $menu_item_value['url'] );
+			if ( '' === $menu_item_value['url'] ) {
+				return new WP_Error( 'invalid_nav_menu_url', __( 'Invalid URL.' ) ); // Fail sanitization if URL is invalid.
+			}
+		}
+
 		if ( 'publish' !== $menu_item_value['status'] ) {
 			$menu_item_value['status'] = 'draft';
 		}