title: Symfony: sfError404Exception: This request has been forwarded to a 404 error page by the action
body: <p>When building a website in Symfony 1.3 my development server refuses to display my custom 404 page.</p>
  
  <p>I have left the config settings as standard, so my error module is the default, as can be seen in my debug toolbar:</p>
  
  <pre><code>sf_error_404_action: error404
  sf_error_404_module: default
  </code></pre>
  
  <p>This request has been forwarded to a 404 error page by the action "article/edit".</p>
  
  <p><strong>Why is my custom 404 page not shown?</strong></p>