uninitialized constant devise::controllers::internalhelpers
===

I'm new to rails and currently working on authentication using devise gem. I would like to communicate with my server from my mobile app. So I'm sending data via JSON. When I tried to sign in it shows me the below error:

  ActionController::RoutingError (uninitialized constant Devise::Controllers::InternalHelpers):
  app/controllers/session_controller.rb:4:in `<class:SessionController>'
  app/controllers/session_controller.rb:1:in `<top (required)>'

 When I was using devise gem version 1.4.6, it was working fine for me. But, I want to make it work with devise version 2.1.0 or later to be able to use any new features that it supports.

If anybody have this running or have any idea please help me. Thanks in advance.

Regards,

Senthil. 

