After upgrade I got several errors:
Volt Bug: "'compileAlways' must be a bool value"
$volt->setOptions( array('compileAlways' => true) );
Groups Router bug: The group of routes does not contain any routes initialize() method not initialized when group mounted
$router->mount(new Frontend())
My class contain:
    use \Phalcon\Mvc\Router\Group;
    class Frontend extends Group
    {
      public function initialize()
      {
          $this->setPaths(
              array(
                  'module' => 'frontend'
              )
          );
          $this->add(
              '/',
              array(
                  'controller'    =>  'index',
                  'action'        =>  'index'
              )
          );
      }
     }