I have class MY_Controller extends CI_Controller and common logic for big profile section, so I\'va tried to create class Profile extends MY_Controller
After some struggle with version 3 and this issue I decided this was not a bad solution...
require_once BASEPATH.'core/Controller.php';
require_once APPPATH.'core/MYCI_Controller.php';
to add this second line where the first exists in the system/core/CodeIgniter.php
[If it's not too late, I recommend strongly against php and/or CodeIgniter.]