title: Shiny server error: No UI defined
body: <p>When I open my shiny application on shiny server, I got an error:</p>
  
  <pre><code>No UI defined
  
  Shiny couldn't find any UI for this application. We looked in:
  
  www/index.html
  ui.R
  </code></pre>
  
  <p>I have checked:</p>
  
  <ul>
  <li>The shiny server is running</li>
  <li>I can run the default hello application.</li>
  <li>I can run my local application without problem.</li>
  <li>I have run the same application before on my shiny server and it worked. However it is not working with the same codes.</li>
  <li>All file under my application have -rw-r--r-- permission.</li>
  </ul>
  
  <p>Can anybody help me with this? Why did it happened? </p>
  
  <p>Thanks in advance!</p>