session_write_close（）：会话回调需要true / false返回值

I'm new to Slim Framework. I'm supposed to work with the previous version of Slim as required by my org. So, I got the existing Slim library and When I run with index.php I get the following error.

Message: session_write_close(): Session callback expects true/false return value
File: C:\xampp\htdocs\slim\Slim\Slim.php
Line: 810

the following is my index.php

require 'Slim/Slim.php';
$app = new Slim();
$app->get('/hello/:name', function ($name) {
echo "Hello, $name";
});
$app->run();

The error traces back to Slim.php

805:   public function stop() {
806:   $flash = $this->view->getData('flash');
807:        if ( $flash ) {
808:          $flash->save();
809:        }
810:        session_write_close();
811:        $this->response->send();
812:        throw new Slim_Exception_Stop();
813:    }

P.s I m completely new to Slim.