Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

vendor/symfony/debug/Exception/ClassNotFoundException.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\Debug\Exception;
+
+/**
+ * Class (or Trait or Interface) Not Found Exception.
+ *
+ * @author Konstanton Myakshin <koc-dp@yandex.ru>
+ */
+class ClassNotFoundException extends FatalErrorException
+{
+    public function __construct($message, \ErrorException $previous)
+    {
+        parent::__construct(
+            $message,
+            $previous->getCode(),
+            $previous->getSeverity(),
+            $previous->getFile(),
+            $previous->getLine(),
+            $previous->getPrevious()
+        );
+        $this->setTrace($previous->getTrace());
+    }
+}