CI3 SESSION

I'm trying to create a custom helper for ci3, and trying to store the values on $_SESSION variable, so i tried to auload session with $autoload['drivers'] = array('session'); on /application/config/autoload.php, but i am getting an error:

A PHP Error was encountered Severity: Notice Message: Undefined: 110

could it be something in my admin controller?

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
class Admin extends CI_Controller {
public function _construct() {
parent::_construct();
}
public function index(){
$this->load->view('Portada');
}
}