Facebook SDK V4 Error - php

Question

I am trying to implement Login with Facebook to my website.
My Code works perfectly fine on Localhost. But when I upload it to server. It gives error like this:
Facebook\FacebookSDKException Object ( [message:protected] => couldn't connect to host [string:Exception:private] => [code:protected]
You can try DEMO: http://dkclan.co/facebook_user_authentication.php
Here is my Code:
<?php
// include required files form Facebook SDK
require 'facebook-php-sdk/autoload.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\Entities\AccessToken;
use Facebook\HttpClients\FacebookCurlHttpClient;
use Facebook\HttpClients\FacebookHttpable;
// start session
session_start();
// init app with app id and secret
FacebookSession::setDefaultApplication( 'abc','xyz' );
// login helper with redirect_uri
$helper = new FacebookRedirectLoginHelper( 'http://dkclan.co/facebook_user_authentication.php' );
// see if a existing session exists
if ( isset( $_SESSION ) && isset( $_SESSION['fb_token'] ) ) {
// create new session from saved access_token
$session = new FacebookSession( $_SESSION['fb_token'] );
// validate the access_token to make sure it's still valid
try {
if ( !$session->validate() ) {
$session = null;
}
} catch ( Exception $e ) {
// catch any exceptions
$session = null;
}
}
if ( !isset( $session ) || $session === null ) {
// no session exists
try {
$session = $helper->getSessionFromRedirect();
} catch( FacebookRequestException $ex ) {
// When Facebook returns an error
// handle this better in production code
print_r( $ex );
} catch( Exception $ex ) {
// When validation fails or other local issues
// handle this better in production code
print_r( $ex );
}
}
// see if we have a session
if ( isset( $session ) ) {
// save the session
$_SESSION['fb_token'] = $session->getToken();
// create a session using saved token or the new one we generated at login
$session = new FacebookSession( $session->getToken() );
// graph api request for user data
$request = new FacebookRequest( $session, 'GET', '/me' );
$response = $request->execute();
// get response
$graphObject = $response->getGraphObject()->asArray();
// print profile data
echo '<pre>' . print_r( $graphObject, 1 ) . '</pre>';
// print logout url using session and redirect_uri (logout.php page should destroy the session)
echo 'Logout';
} else {
// show login url
echo 'Login';
}
Any idea why I am getting this error?

Answer 1

Most likely your provider blocks outgoing CURL calls (the Facebook SDK uses CURL for calls to the Facebook API).
See this thread with the same error: https://stackoverflow.com/questions/9425406/facebook-api-exception-object-error-on-facebook-app
It makes sense as it works on your local server. The only thing you can do is ask your provider to allow calls to the Facebook API.