title: Failed to OpenActiveSession with "an unknown error occurred" at iOS Facebook SDK
body: <p>I'm trying to integrate facebook into iPhone app using Xamarin MonoTouch.
  I'm using this SDK component:
  <a href="http://components.xamarin.com/view/facebookios" rel="nofollow">http://components.xamarin.com/view/facebookios</a></p>
  
  <pre><code>var activeSessionOpened = FBSession.OpenActiveSession(false);
  Debug.WriteLine("Active Session Opened: {0}", activeSessionOpened);
  
  activeSessionOpened = FBSession.OpenActiveSession(new string[] { }, true,
      (session, status, error) =&gt;
      {
          Debug.WriteLine("Active Session State Changed. Status: {0}. Error: {1}", status, error.DebugDescription);
      });
  </code></pre>
  
  <p>Every time during 2nd request to OpenActiveSession I'm getting the following error:</p>
  
  <blockquote>
    <p>"Error Domain=com.facebook.sdk Code=2 \"The operation couldn’t be
    completed. (com.facebook.sdk error 2.)\" UserInfo=0x1e081e60
    {com.facebook.sdk:ErrorLoginFailedReason=com.facebook.sdk:SystemLoginCancelled,
    com.facebook.sdk:ErrorInnerErrorKey=Error Domain=com.apple.accounts
    Code=7 \"<strong>The Facebook server could not fulfill this access request: An
    unknown error occurred\"</strong> UserInfo=0x1cdba190
    {NSLocalizedDescription=The Facebook server could not fulfill this
    access request: An unknown error occurred},
    com.facebook.sdk:ErrorSessionKey=,
    expirationDate: (null), refreshDate: (null), attemptedRefreshDate:
    0001-12-30 00:00:00 +0000, permissions:(null)>}"</p>
  </blockquote>
  
  <p>Sample here:
  <a href="https://dl.dropboxusercontent.com/u/19503836/iPhoneFace2.zip" rel="nofollow">https://dl.dropboxusercontent.com/u/19503836/iPhoneFace2.zip</a></p>
  
  <p>I appreciate any suggestion and help.
  Thanks!</p>