Phalcon 3.4.1 to Phalcon 4.1.2 upgrade issue on Session assign Model

[mahen3d]

// in the controller I used to do below to assign the User model to the session.
                    $this->session->user = $user;

//while initial session load, as below.
$di->setShared('session' , function () use ($config) {
            $options = [
                "uniqueId"   => $config->site->redis_uid,
                "host"       =>  $config->site->redis_host,
                "port"       =>  $config->site->redis_port,
                'autoStart'   => true,
                //"auth"       => $config->site->redis_pass,
                "persistent" => true,
                "lifetime"   => 3600,
                "prefix"     => $config->site->redis_uid."_",
                "index"      => 0,
            ];
            $session           = new \Phalcon\Session\Manager();
            $serializerFactory = new \Phalcon\Storage\SerializerFactory();
            $factory           = new \Phalcon\Storage\AdapterFactory($serializerFactory);
            $redis             = new \Phalcon\Session\Adapter\Redis($factory, $options);
            if(session_status() === PHP_SESSION_NONE ){
                $session
                    ->setAdapter($redis)
                    ->start();
            }
            return $session;
        });

But after upgrading to the phalcon version 4.1.2 I found this line

$this->session->user = $user;

It no longer works and gives me a 502 Gateway Error for some unknown reason, while I don't have any

1. Php errors
2. Applications Errors (no catch exceptions)
3. Nginx Server Errors

Any ideas on this?