Browser return "The connection was reset" when use Validation

My purpose like this: https://stackoverflow.com/questions/21666082/phalcon-validation-doesnt-work-not-in-model

I want to validate when form login submit. When submit, i get message error from browser: "The connection was reset".

use Models\Glang\User;
use Phalcon\Validation\Validator\Email;

class LoginController extends \Phalcon\Mvc\Controller{
  public function indexAction($username = null, $password = null){

    $validation = new \Phalcon\Validation();
    $validation->add('email', new Email(array(
        'message' => 'The e-mail is not valid'
    )));
    $messages = $validation->validate($_POST);
    if (count($messages)) {
        foreach ($messages as $message) {
        echo $message, '<br>';
     }
     exit;
     }
   }
 }