Codeigniter, facebook SDK 5, not working - php

Question

I have followed this tutorial https://www.sammyk.me/upgrading-the-facebook-php-sdk-from-v4-to-v5 and so far I have managed to integrate the SDK into codeignitor etc
In my controller I have
function facebook(){
require_once __DIR__ . '/../vendor/autoload.php';
$fb = new Facebook\Facebook([
'app_id' => 'xxx',
'app_secret' => 'xxx',
'default_graph_version' => 'v2.5',
]);
$helper = $fb->getRedirectLoginHelper();
$permissions = ['email', 'user_posts']; // optional
$callback = 'http://localhost/project/api/index.php/social/facebook-callback';
$loginUrl = $helper->getLoginUrl($callback, $permissions);
echo $loginUrl;
}
And this generates a url for me. I then follow this link and it takes me to facebook I click ok then it goes to a redirect page.
On that page i have
function facebook_callback(){
require_once __DIR__ . '/../vendor/autoload.php';
$fb = new Facebook\Facebook([
'app_id' => 'xxx',
'app_secret' => 'xxx',
'default_graph_version' => 'v2.5',
]);
$helper = $fb->getRedirectLoginHelper();
try {
$accessToken = $helper->getAccessToken();
} catch(Facebook\Exceptions\FacebookSDKException $e) {
// There was an error communicating with Graph
echo $e->getMessage();
exit;
}
if (isset($accessToken)) {
// User authenticated your app!
// Save the access token to a session and redirect
$_SESSION['facebook_access_token'] = (string) $accessToken;
// Log them into your web framework here . . .
// Redirect here . . .
exit;
} elseif ($helper->getError()) {
// The user denied the request
// You could log this data . . .
var_dump($helper->getError());
var_dump($helper->getErrorCode());
var_dump($helper->getErrorReason());
var_dump($helper->getErrorDescription());
// You could display a message to the user
// being all like, "What? You don't like me?"
exit;
}
// If they've gotten this far, they shouldn't be here
http_response_code(400);
exit;
}
When I land on the page I get as an error
Cross-site request forgery validation failed. Required param "state" missing.
Why does this happen? Is this to do with the sessions? I have followed the tutorial and nothing seems to work. Any other documents I have found I have tried to for example session_start(); and Overwriting Persistent Data but to no avail!
Any point in the right direction will be very much appreciated. I have googled this loads and there are no clear answers.
Best regards

Answer 1

Ok answer found!
Pay special attention to the Overwriting Persistent Data in the tutorial! So it is a session related issue. Also doing it late at night is ill-advised.
What I missed was that you have to start the process from scratch, ie facebook route and get a brand new url link, then paste that link in the url, and you will be redirected to the facebook_callback. And you will then get the data you require.
Answer here incase someone else falls in the "what the hell is going on (when late at night trap)!"