Update to Drupal 8.1.0. For more information, see https://www.drupal.org/drupal-8.1.0-release-notes

vendor/symfony/http-kernel/DataCollector/AjaxDataCollector.php

@@ -0,0 +1,33 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\HttpKernel\DataCollector;
+
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+/**
+ * AjaxDataCollector.
+ *
+ * @author Bart van den Burg <bart@burgov.nl>
+ */
+class AjaxDataCollector extends DataCollector
+{
+    public function collect(Request $request, Response $response, \Exception $exception = null)
+    {
+        // all collecting is done client side
+    }
+
+    public function getName()
+    {
+        return 'ajax';
+    }
+}