title: HEROKU Application Err - Application error An error occurred in the application and your page could not be served
body: <p>I'm looking a solution for my stupid problems.
  I use Heroku to deployed my application. After I linked to github,I got this error when open my application:</p>
  
  <blockquote>
    <p>Application error An error occurred in the application and your page
    could not be served. If you are the application owner, check your logs
    for details. You can do this from the Heroku CLI with the command
    heroku logs --tail</p>
  </blockquote>
  
  <p>I tried to research the solution but nothing worked.
  My config in app.js</p>
  
  <pre><code>port = process.env.PORT || config.__port_server,
  app.listen(port)
  </code></pre>
  
  <p>thank you</p>