title: Facebook SDK 3.1 - Error validating access token
body: <p>I'm trying to transition my app to the new Facebook SDK 3.1 (with support for iOS6 authentication).</p>
  
  <p>I had it working just fine, so I then decided to remove the app from my list of authorized apps on the FB website in order to test that iOS would ask for permission again.</p>
  
  <p>Now my first call to <code>[FBRequest requestForMe]</code> causes this error:</p>
  
  <p>Response:</p>
  
  <pre><code>{
    "error": {
      "message": "Error validating access token: Session does not match current stored session. This may be because the user changed the password since the time the session was created or Facebook has changed the session for security reasons.",
      "type":"OAuthException",
      "code":190,
      "error_subcode":460
    }
  }
  </code></pre>
  
  <p>Some details:</p>
  
  <p>I'm trying to open the session as follows :</p>
  
  <pre><code>   [FBSession openActiveSessionWithReadPermissions:nil
                                         allowLoginUI:YES
                                    completionHandler:^(FBSession *session, FBSessionState state, NSError *error) {
  
                                             switch (state) {
                                                 case FBSessionStateOpen:
                                                     [self presentPostOptions];
                                                     break;
  
                                                 case FBSessionStateClosed:
                                                 case FBSessionStateClosedLoginFailed:
                                                     [FBSession.activeSession closeAndClearTokenInformation];
                                                     break;
  
                                                 default:
                                                     break;
                                             }
  </code></pre>
  
  <p>I then get called back in state <code>FBSessionStateOpen</code> (at this point iOS hasn't presented a request dialog, is that to be expected)? Facebook logs this:</p>
  
  <pre><code>2012-09-26 13:43:43.768 MyApp[2177:907] FBSDKLog: FBSession INVALID transition from FBSessionStateCreated to FBSessionStateClosed
  2012-09-26 13:43:43.769 MyApp[2177:907] FBSDKLog: FBSession transition from FBSessionStateCreated to FBSessionStateCreatedOpening 
  2012-09-26 13:43:43.837 MyApp[2177:907] FBSDKLog: FBSession transition from FBSessionStateCreatedOpening to FBSessionStateOpen 
  </code></pre>
  
  <p>Once the session is open, in presentPostOptions I do this:</p>
  
  <pre><code>- (void)presentPostOptions
  {    
      [[FBRequest requestForMe] startWithCompletionHandler:^(FBRequestConnection *connection, NSDictionary&lt;FBGraphUser&gt; *user, NSError *error) {
          if (!error) {
              self.usersName = user.name;
              self.usersID = user.id;
  
              [self getPages];
          }
          else
          {
              [self didFailWithError:error];
          }
      }];
  }
  </code></pre>
  
  <p>Before the above completion block is called back, my main state handler block is called with an <code>FBSessionStateClosed</code> state. In the meantime, the Facebook SDK has logged the above error.</p>
  
  <p>I can't find any way to reset the system; nor do I really understand the cause.</p>
  
  <p>Can anyone please shed some light?</p>