Update to Drupal 8.0.0 beta 14. For more information, see https://drupal.org/node/2544542

sites/default/default.settings.php

@@ -632,6 +632,15 @@ if ($settings['hash_salt']) {
  */
 $settings['container_yamls'][] = __DIR__ . '/services.yml';
 
+/**
+ * Override the default service container class.
+ *
+ * This is useful for example to trace the service container for performance
+ * tracking purposes, for testing a service container with an error condition or
+ * to test a service container that throws an exception.
+ */
+# $settings['container_base_class'] = '\Drupal\Core\DependencyInjection\Container';
+
 /**
  * Trusted host configuration.
  *