title: Error deploying Phoenix app in production
body: <p>I was trying to start a Phoenix app in production mode in a VPS (in development mode is OK) so, after compiling my application assets, I run:</p>
  
  <pre><code>PORT=4001 MIX_ENV=prod mix phoenix.server
  </code></pre>
  
  <p>and I get:</p>
  
  <pre><code>** (Mix) Could not start application myapp: could not find application file: myapp.app
  </code></pre>
  
  <p>What should I do?</p>