title: Oauth2 Instagram API "redirect URI does not match registered redirect URI"
body: <p>I am working on a Rails application which is in development mode and it can register with omniauth. </p>
  
  <p>The host is </p>
  
  <pre><code>http://localhost:3000/
  </code></pre>
  
  <p>I'm using the gems:</p>
  
  <pre><code>gem 'omniauth'
  gem 'omniauth-foursquare'
  gem 'omniauth-instagram'
  </code></pre>
  
  <p>When I register through omniauth with Foursquare there's no problem at all. All the settings are right and my redirect_uri in the Foursquare developer settings equals to the host (localhost:3000)</p>
  
  <p>However, if I fill in the exact same redirect_uri (localhost:3000) in the Instagram client manager*. Instagram gives me this:</p>
  
  <pre><code>{
   "code": 400,
   "error_type": "OAuthException",
   "error_message": "Redirect URI does not match registered             redirect URI"
  }
  </code></pre>
  
  <p>Based upon this URL:</p>
  
  <pre><code>https://instagram.com/oauth/authorize?response_type=code&amp;client_id=&lt;ID&gt;&amp;redirect_uri=http%3A%2F%2Flocalhost%3A3000%2Fauth%2Finstagram%2Fcallback&amp;state=18415adf24dd97873e61094f67c0fb7a94857fedf93e9d2e&amp;scope=basic
  </code></pre>
  
  <p>*
  <img src="https://i.stack.imgur.com/Jjj0J.png" alt="enter image description here"></p>
  
  <p>What am I doing wrong according to Instagram and how should this be fixed?</p>