title: Symfony 2.8.2 flashmessage and redirecttoroute
body: <p>I'm using Symfony 2.8.2 and somehow the FlashMessage does not live through a redirect.</p>
  
  <pre><code>$this-&gt;addFlash('success', 'Expedition erfolgreich!');
  return $this-&gt;redirectToRoute('mainmenu_dashboard');
  </code></pre>
  
  <p>After the redirect there is no flashmessage. I already looked in the session (dumped it) but there is no flash message after the redirect.</p>
  
  <p>Any ideas?</p>