Facebook Login Returning NULL

Question

Good evening, I’m implementing Facebook login in my application.

But the line below always returns NULL

$session = $helper->getSessionFromRedirect();

Someone knows what could be wrong?

Below the full code:

<?php

session_start();
// added in v4.0.0
require_once './autoload.php';

use Facebook\FacebookSession;
use Facebook\FacebookRedirectLoginHelper;
use Facebook\FacebookRequest;
use Facebook\FacebookRequestException;

// init app with app id and secret
FacebookSession::setDefaultApplication('{id}', '{secret}');
// login helper with redirect_uri
$helper = new FacebookRedirectLoginHelper('http://localhost/PedeAqui');

try {
    $session = $helper->getSessionFromRedirect();

} catch (FacebookRequestException $ex) {
    var_dump($ex);
} catch (Exception $ex) {
    var_dump($ex);
}
// see if we have a session
if (isset($session)) {
    // graph api request for user data
    $request = new FacebookRequest($session, 'GET', '/me');
    $response = $request->execute();
    // get response
    $request = new FacebookRequest($session, 'GET', '/me?fields=email,first_name,last_name,gender,name,id');
    $response = $request->execute();
    $fbid = $graphObject->getProperty('id');              // To Get Facebook ID
    $fbfullname = $graphObject->getProperty('name'); // To Get Facebook full name
    $femail = $graphObject->getProperty('email');    // To Get Facebook email ID
    /* ---- Session Variables ----- */
    $_SESSION['cod_usuario'] = $fbid;
    $_SESSION['usuario'] = $fbfullname;
    $_SESSION['email'] = $femail;
    $_SESSION['tipo'] = 2;
    /* ---- header location after session ---- */
    header("Location: http://localhost/PedeAqui/index.php");
} else {
    $loginUrl = $helper->getLoginUrl();
    header("Location: " . $loginUrl);
}
?>