diff -u b/core/lib/Drupal/Core/Config/StorageComparer.php b/core/lib/Drupal/Core/Config/StorageComparer.php
--- b/core/lib/Drupal/Core/Config/StorageComparer.php
+++ b/core/lib/Drupal/Core/Config/StorageComparer.php
@@ -134,7 +134,7 @@
       // ensure the array is keyed from 0.
       $this->changelist[$op] = array_values(array_intersect($sort_order, $this->changelist[$op]));
       if ($count != count($this->changelist[$op])) {
-        throw \InvalidArgumentException(String::format('Sorting the @op changelist should not change its length.', array('@op' => $op)));
+        throw new \InvalidArgumentException(String::format('Sorting the @op changelist should not change its length.', array('@op' => $op)));
       }
     }
   }