title: Angular 4 error - ERROR in ./src/main.ts Module not found: Error: Can't resolve './$$_gendir/app/app.module.ngfactory'
body: <p>During the angular build for production (<code>ng build --prod</code>) I get this error:</p>
  
  <pre><code>ERROR in ./src/main.ts
  Module not found: Error: Can't resolve './$$_gendir/app/app.module.ngfactory' in '/Applications/MAMP/htdocs/bandpay/stg-bandpay-client/src'
   @ ./src/main.ts 3:0-74
   @ multi ./src/main.ts
  
  ....
  </code></pre>
  
  <p>what does that mean, how to resolve that?</p>