Call to a member function login() on null

When I am using cakephp 2.0.2 login works fine with $this->Auth->login(). But when I am using cakephp 2.8.8 I got the internal error and it was Call to a member function login() on null.

Is there any new something in cakephp 2.8.8 instead of using $this->Auth->login(). Please help me

me too, you done? please help me