title: OmniAuth Invalid Response Error
body: <p>I'm using OmniAuth with Devise to allow users to login with facebook or to create a normal account with a username and password. When I originally set it all up I used the excellent directions from <a href="http://railscasts.com/episodes/235-omniauth-part-1" rel="nofollow">Railscasts</a>. Everything was working very nicely for 2+ months but just the other day the facebook login stopped working. OmniAuth sends you away to the authentication with facebook and then returns with: <code>http://localhost:3000/auth/failure?message=invalid_response</code></p>
  
  <p>Google has no suggestions on what causes this error or how to fix it and the OmniAuth docs don't either. I've tried digging through their code as well but the only mention of this error I've found is this, in <code>/oa-oauth/lib/omniauth/strategies/oauth.rb</code>:</p>
  
  <pre><code>rescue ::MultiJson::DecodeError =&gt; e
    fail!(:invalid_response, e)
  end
  </code></pre>
  
  <p>Has anyone ever seen this error!? Know what it is or how to fix it?! This is keeping me from launching this application so any help would be very very appreciated! </p>
  
  <p>Thanks,
  JG</p>