Routing error when updating to Rails 3.2.6 or Rspec 2.11.0

After upgrading to Rails 3.2.6 or Rspec 2.11.0, my specs starts to show routing errors like the following:

  4) UsersController GET activate activation code not exist 
     Failure/Error: subject{ get :activate }
     ActionController::RoutingError:
       No route matches {:controller=>"users", :action=>"activate"}

There is also a after each hook error

An error occurred in an after(:each) hook
  RSpec::Mocks::MockExpectationError: (#<EmailSubscriber[...]>).update_attributes({:enable=>true})
    expected: 1 time
    received: 0 times
  occurred at [...]/spec/controllers/users_controller_spec.rb:75:in `block (3 levels) in <top (required)>'

The application in development mode still runs fine.