title: Troubleshooting "The controller for URI is not callable" error
body: <p>I'm working on <strong>Symfony 2.3</strong> and I declared a new <strong>route</strong> and new <strong>controller</strong>, but when I call this controller from the browser I get this error:</p>
  <p><code>The controller for URI &quot;/user/1&quot; is not callable. in /dev.mydomain.org/vendor/symfony/symfony/src/Symfony/Component/HttpKernel/Controller/ControllerResolver.php at line 82</code></p>
  <p>This is my simple <strong>route</strong> configuration:</p>
  <pre class="lang-yaml prettyprint-override"><code>user_homepage:
      pattern:  /user
      defaults: { _controller: UserBundle:Default:index }
      
  user_show:
      pattern:  /user/{id}
      defaults: { _controller: UserBundle:Default:show }
      requirements:
          id:  \d+
  </code></pre>
  <p>And this is my very simple <strong>controller</strong>:</p>
  <pre class="lang-php prettyprint-override"><code>public function showUserAction($id)
  {        
      return $this-&gt;render('UserBundle:Default:show.html.twig', array());
  }
  </code></pre>
  <p>What is wrong?</p>