title: What does NS_ERROR_UNKNOWN_PROTOCOL mean?
body: <p>I am doing a AJAX request using Angular 1.5.9. The code looks like this:</p>
  
  <pre><code>$http.get('localhost:8080/app/users').then(function(resp) { ... });
  </code></pre>
  
  <p>Why do I get this error?</p>
  
  <p>"NS_ERROR_UNKNOWN_PROTOCOL" (...)
  stack: "createHttpBackend/&lt;@<a href="http://localhost:8080/app/libraries/angular.js:12115:5" rel="nofollow noreferrer">http://localhost:8080/app/libraries/angular.js:12115:5</a> ..."</p>
  
  <p>The url exists and can be accessed from the browser.</p>