Создание страницы регистрации с Heroku - ошибки NotFoundException

Я пытаюсь создать основную страницу регистрации учетной записи для веб-сайта с использованием Heroku. Я установил PostGRESQL и создал таблицу с именами пользователей со всеми соответствующими столбцами. (Я еще не использовал шифрование, так как я просто пытаюсь получить эту работу в первую очередь.) Вот мой PHP для страницы:

<?php
require('../vendor/autoload.php');
require('../includes/config.php');
$app = new Silex\Application();
$app['debug'] = true;
// Register the monolog logging service
$app->register(new Silex\Provider\MonologServiceProvider(), array(
'monolog.logfile' => 'php://stderr',
));
// Register the Twig templating engine
$app->register(new Silex\Provider\TwigServiceProvider(), array(
'twig.path' => __DIR__.'/../views',
));

/*checking database*/
    // if form was submitted
    if ($_SERVER["REQUEST_METHOD"] == "POST")
    {
         /**/
        //check that all three fields have been filled out
        if (empty($_POST["username"])||empty($_POST["password"])||empty($_POST["confirmation"]))         
        {     
             apologize("You need to complete the username, password, and confirmation fields.");
             exit;
        }       
        //check that password and confirmation are the same
        if ($_POST["password"] != $_POST["confirmation"])
        {
             apologize("Password and confirmation must match.");
             exit;
        }

        if (!filter_var($_POST["email"], FILTER_VALIDATE_EMAIL) )
        {
             apologize("Email address not valid. Try again.");        
             exit ; 
        }    


// Register the Postgres database add-on
$dbopts = parse_url(getenv('DATABASE_URL'));
$app->register(new Herrera\Pdo\PdoServiceProvider(),
array   (
    'pdo.dsn' => 'pgsql:dbname='.ltrim($dbopts["path"],'/').';host='.$dbopts["host"],
    'pdo.port' => $dbopts["port"],
    'pdo.username' => $dbopts["user"],
    'pdo.password' => $dbopts["pass"]
    )
          );

$st = $app['pdo']->prepare('INSERT INTO users (username, email, hash) VALUES ('. $_POST["username"] . ', ' . $_POST["email"]. ', '. $_POST["password"]. ')');
$st->execute();     

$app->get('/db/', function() use($app) {

$st = $app['pdo']->prepare('SELECT username FROM users');
$st->execute();
$names = array();
while ($row = $st->fetch(PDO::FETCH_ASSOC)) {
$app['monolog']->addDebug('Row ' . $row['name']);
$names[] = $row;
}
return $app['twig']->render('database.twig', array(
'names' => $names
));
});
$app->get('/twig/{name}', function($name) use($app) {
return $app['twig']->render('index.twig', array(
'name' => $name,
));
});
$app->run();
         //if the registration worked, log the user in
       if ($result !== false)
       {
            //if registration worked, remember that session ID
            $rows = query("SELECT LAST_INSERT_ID() AS id");
            $id = $rows[0]["id"];

            $_SESSION["id"] = $id; 
            redirect("../index.php");
       }
    }
    else
    {
        // else render form
        render("register_form.php", ["title" => "Register"]);
    }

?>

При отправке страницы я получаю следующие ошибки:

Извините, страница, которую вы ищете, не найдена. 2/2 NotFoundHttpException в строке RouterListener.php 145: маршрут "POST/" не найден (из " http://secret-ridge-6332.herokuapp.com/register.php ")

in RouterListener.php line 145
at RouterListener->onKernelRequest(object(GetResponseEvent), 'kernel.request', object(EventDispatcher))
at call_user_func(array(object(RouterListener), 'onKernelRequest'), object(GetResponseEvent), 'kernel.request', object(EventDispatcher)) in EventDispatcher.php line 164
at EventDispatcher->doDispatch(array(array(object(RouterListener), 'onKernelRequest'), array(object(LocaleListener), 'onKernelRequest'), array(object(LogListener), 'onKernelRequest'), array(object(MiddlewareListener), 'onKernelRequest')), 'kernel.request', object(GetResponseEvent)) in EventDispatcher.php line 53
at EventDispatcher->dispatch('kernel.request', object(GetResponseEvent)) in HttpKernel.php line 126
at HttpKernel->handleRaw(object(Request), '1') in HttpKernel.php line 66
at HttpKernel->handle(object(Request), '1', true) in Application.php line 538
at Application->handle(object(Request)) in Application.php line 515
at Application->run() in register.php line 72

1/2 ResourceNotFoundException в строке UrlMatcher.php 96:

in UrlMatcher.php line 96
at UrlMatcher->match('/') in RedirectableUrlMatcher.php line 30
at RedirectableUrlMatcher->match('/') in LazyUrlMatcher.php line 51
at LazyUrlMatcher->match('/') in RouterListener.php line 127
at RouterListener->onKernelRequest(object(GetResponseEvent), 'kernel.request', object(EventDispatcher))
at call_user_func(array(object(RouterListener), 'onKernelRequest'), object(GetResponseEvent), 'kernel.request', object(EventDispatcher)) in EventDispatcher.php line 164
at EventDispatcher->doDispatch(array(array(object(RouterListener), 'onKernelRequest'), array(object(LocaleListener), 'onKernelRequest'), array(object(LogListener), 'onKernelRequest'), array(object(MiddlewareListener), 'onKernelRequest')), 'kernel.request', object(GetResponseEvent)) in EventDispatcher.php line 53
at EventDispatcher->dispatch('kernel.request', object(GetResponseEvent)) in HttpKernel.php line 126
at HttpKernel->handleRaw(object(Request), '1') in HttpKernel.php line 66
at HttpKernel->handle(object(Request), '1', true) in Application.php line 538
at Application->handle(object(Request)) in Application.php line 515
at Application->run() in register.php line 72

Любые идеи, что я могу делать неправильно? Спасибо!