Error installing Vanilla 2.5 in Digital Ocean Ubuntu 16.04

Hi All.
I've trying to execute vanilla installer in a Ubuntu 16.04.3 LTS (GNU/Linux 4.4.0-112-generic x86_64) Droplet in digital Ocean.
When i try to run installer from my droplet ip i get following error.

// Report and track all errors.
error_reporting(E_ERROR | E_PARSE | E_CORE_ERROR | E_COMPILE_ERROR | E_USER_ERROR | E_RECOVERABLE_ERROR);
ini_set('display_errors', 0);
ini_set('track_errors', 1);

ob_start();

// Minimal environment needed to use most of Vanilla's framework.
require_once(DIR.'/environment.php');

// Require the bootstrap to configure the application.
require_once(DIR.'/bootstrap.php');

// Create and configure the dispatcher.
$dispatcher = Gdn::dispatcher();

// Process the request.
$dispatcher->start();
$dispatcher->dispatch();

Thanks to all in advance.