404, controller's method not called

I am trying to solve a problem of 404 in my application. The problem occurs because of problem in core/Codeigniter.php:
echo 'BEFORE call_user_func_array';
var_dump($CI, $method, $params);
call_user_func_array(array(&$CI, $method), $params);

// Mark a benchmark end point
$BM->mark('controller_execution_time_( '.$class.' / '.$method.' )_end');
echo 'AFTER call_user_func_array ';

BEFORE is displayed, AFTER is not displayed.
var_dump displays object Main, method index, empty array params.
I have a controller
class Main extends MY_Controller {
public function index() {
...

Please help.