In http://symfony.com/doc/current/cookbook/debugging.html#disabling-the-bootstrap-file-and-class-caching say that you can disable the generation of the class cache by removing the call to the loadClassCache() method from the Kernel class. However, this is no longer true with the new ClassCacheCacheWarmer that was introduced in Symfony 2.8 and generates the class cache when the application cache is warmed up (see also symfony/symfony#17439).