Facebook PHP SDK exception error

Question

I am getting an interesting SDK exception message from FB's PHP SDK. I set up my code exactly as the FB docs say to do..?

DEBUG ERROR MESSAGE:

[12-Jun-2014 21:08:12 UTC] PHP Fatal error:  Uncaught exception 'Facebook\FacebookSDKException' with message 'Session not active, could not store state.' in C:\WebRoot\Website\root\inc\Facebook\FacebookRedirectLoginHelper.php:188
Stack trace:
#0 C:\WebRoot\Website\root\inc\Facebook\FacebookRedirectLoginHelper.php(94):Facebook\FacebookRedirectLoginHelper->storeState('**********...')
#1 C:\WebRoot\Website\root\login\index.php(87): Facebook\FacebookRedirectLoginHelper->getLoginUrl()
#2 {main}
   thrown in C:\WebRoot\Website\root\inc\Facebook\FacebookRedirectLoginHelper.php on line 188

Facebook.php:

<?php
require_once("../inc/config.php");
require_once(ROOT_PATH . 'inc/Facebook/FacebookSession.php' );
require_once(ROOT_PATH . 'inc/Facebook/FacebookRedirectLoginHelper.php' );
require_once(ROOT_PATH . 'inc/Facebook/FacebookRequest.php' );
require_once(ROOT_PATH . 'inc/Facebook/FacebookResponse.php' );
require_once(ROOT_PATH . 'inc/Facebook/FacebookSDKException.php' );
require_once(ROOT_PATH . 'inc/Facebook/FacebookRequestException.php' );
require_once(ROOT_PATH . 'inc/Facebook/FacebookAuthorizationException.php' );
require_once(ROOT_PATH . 'inc/Facebook/GraphObject.php' );
require_once(ROOT_PATH . 'inc/Facebook/HttpClients/FacebookCurl.php' );
require_once(ROOT_PATH . 'inc/Facebook/HttpClients/FacebookHttpable.php' );
require_once(ROOT_PATH . 'inc/Facebook/HttpClients/FacebookCurlHttpClient.php' );

use Facebook\FacebookSession;

// init app with app id (APPID) and secret (SECRET)
FacebookSession::setDefaultApplication("**********","*******************");

Main Login Page:

<?php
require_once("../inc/config.php");
require_once(ROOT_PATH . 'inc/Facebook/Facebook.php' );
require_once(ROOT_PATH . "inc/LoginHelper.php");

use Facebook\FacebookSession;
use Facebook\FacebookRedirectLoginHelper;
use Facebook\FacebookRequest;
use Facebook\FacebookResponse;
use Facebook\FacebookSDKException;
use Facebook\FacebookRequestException;
use Facebook\FacebookAuthorizationException;
use Facebook\GraphObject;
use Facebook\HttpClients\FacebookCurl;
use Facebook\HttpClients\FacebookHttpable;
use Facebook\HttpClients\FacebookCurlHttpClient;

session_start();

// login helper with redirect_uri
$helper = new FacebookRedirectLoginHelper( '***********' );

Link on main login page:

<a href="<?php echo $helper->getLoginUrl();?>"><img src="<?php echo BASE_URL; ?>img/facebook-login-button.png" class="fb-login"></a>

Redirect url page:

<?php
require_once("../inc/config.php");
require_once(ROOT_PATH . 'inc/Facebook/Facebook.php' );

use Facebook\FacebookSession;
use Facebook\FacebookRedirectLoginHelper;
use Facebook\FacebookRequest;
use Facebook\FacebookResponse;
use Facebook\FacebookSDKException;
use Facebook\FacebookRequestException;
use Facebook\FacebookAuthorizationException;
use Facebook\GraphObject;
use Facebook\HttpClients\FacebookCurl;
use Facebook\HttpClients\FacebookHttpable;
use Facebook\HttpClients\FacebookCurlHttpClient;

session_start();

//get user login token from FB
$helper = new FacebookRedirectLoginHelper('*******');
try {
   $session = $helper->getSessionFromRedirect();
} catch(FacebookRequestException $ex) {
     echo $ex;
  // When Facebook returns an error
} catch(Exception $ex) {
    echo $ex;
  // When validation fails or other local issues
}
if ($session) {
    $FacebookAccessToken = $session->getToken();
   // Logged in
}

Answer 1

Put session_start(); on the TOP of your file