Posting to Facebook via Website Application - Internal Server Error - php

Question

I am using the following code to get a User's posts, with APP_ID, and APP_SECRET replaced with the appropriate fields.
<?php
session_start();
require_once __DIR__ . '/src/Facebook/autoload.php';
$fb = new Facebook\Facebook([
'app_id' => 'APP_ID',
'app_secret' => 'APP_SECRET',
'default_graph_version' => 'v2.5',]);
$helper = $fb->getCanvasHelper();
$permissions = ['user_posts']; // optionnal
try {
if (isset($_SESSION['facebook_access_token'])) {
$accessToken = $_SESSION['facebook_access_token'];
} else {
$accessToken = $helper->getAccessToken();
}
} catch(Facebook\Exceptions\FacebookResponseException $e) {
// When Graph returns an error
echo 'Graph returned an error: ' . $e->getMessage();
exit;
} catch(Facebook\Exceptions\FacebookSDKException $e) {
// When validation fails or other local issues
echo 'Facebook SDK returned an error: ' . $e->getMessage();
exit;
}
if (isset($accessToken)) {
if (isset($_SESSION['facebook_access_token'])) {
$fb->setDefaultAccessToken($_SESSION['facebook_access_token']);
} else {
$_SESSION['facebook_access_token'] = (string) $accessToken;
// OAuth 2.0 client handler
$oAuth2Client = $fb->getOAuth2Client();
// Exchanges a short-lived access token for a long-lived one
$longLivedAccessToken = $oAuth2Client->getLongLivedAccessToken($_SESSION['facebook_access_token']);
$_SESSION['facebook_access_token'] = (string) $longLivedAccessToken;
$fb->setDefaultAccessToken($_SESSION['facebook_access_token']);
}
// validating the access token
try {
$request = $fb->get('/me');
} catch(Facebook\Exceptions\FacebookResponseException $e) {
// When Graph returns an error
if ($e->getCode() == 190) {
unset($_SESSION['facebook_access_token']);
$helper = $fb->getRedirectLoginHelper();
$loginUrl = $helper->getLoginUrl('https://apps.facebook.com/APP_NAMESPACE/', $permissions);
echo "<script>window.top.location.href='".$loginUrl."'</script>";
exit;
}
} catch(Facebook\Exceptions\FacebookSDKException $e) {
// When validation fails or other local issues
echo 'Facebook SDK returned an error: ' . $e->getMessage();
exit;
}
// getting all posts published by user
try {
$posts_request = $fb->get('/me/posts?limit=500');
} catch(Facebook\Exceptions\FacebookResponseException $e) {
// When Graph returns an error
echo 'Graph returned an error: ' . $e->getMessage();
exit;
} catch(Facebook\Exceptions\FacebookSDKException $e) {
// When validation fails or other local issues
echo 'Facebook SDK returned an error: ' . $e->getMessage();
exit;
}
$total_posts = array();
$posts_response = $posts_request->getGraphEdge();
if($fb->next($posts_response)) {
$response_array = $posts_response->asArray();
$total_posts = array_merge($total_posts, $response_array);
while ($posts_response = $fb->next($posts_response)) {
$response_array = $posts_response->asArray();
$total_posts = array_merge($total_posts, $response_array);
}
print_r($total_posts);
} else {
$posts_response = $posts_request->getGraphEdge()->asArray();
print_r($posts_response);
}
// Now you can redirect to another page and use the access token from $_SESSION['facebook_access_token']
} else {
$helper = $fb->getRedirectLoginHelper();
$loginUrl = $helper->getLoginUrl('https://apps.facebook.com/APP_NAMESPACE/', $permissions);
echo "<script>window.top.location.href='".$loginUrl."'</script>";
}
When I run it locally on command line (php post.php), I get the following:
<script>window.top.location.href='https://www.facebook.com/v2.5/dialog/oauth?client_id=843019182480437&state=bb8b088f64641baed7d1e4de734ad19b&response_type=code&sdk=php-sdk-5.1.2&redirect_uri=https%3A%2F%2Fapps.facebook.com%2FAPP_NAMESPACE%2F&scope=user_posts
Which means the syntax is correct. When I go to the link I get the following notification by Facebook:
Given URL is not allowed by the Application configuration: One or more of the given URLs is not allowed by the App's settings. It must match the Website URL or Canvas URL, or the domain must be a subdomain of one of the App's domains.
I have set the Website URL to the appropriate value. When I try to access post.php from my server I get an internal server error.
Has anyone else experienced this before?