Rails 4 - Circular dependency detected while autoloading constant Users::TodosController - ruby-on-rails-4

Question

besides using devise for authentification w standard Devise routes.. , I added the follwoing
namespace :users do
resources :todos
end
to magane todos for the current user.
the generated routes are fine ...
users_todos GET /users/todos(.:format) users/todos#index
POST /users/todos(.:format) users/todos#create
new_users_todo GET /users/todos/new(.:format) users/todos#new
edit_users_todo GET /users/todos/:id/edit(.:format) users/todos#edit
users_todo GET /users/todos/:id(.:format) users/todos#show
PATCH /users/todos/:id(.:format) users/todos#update
PUT /users/todos/:id(.:format) users/todos#update
DELETE /users/todos/:id(.:format) users/todos#destroy
once the user is logged in , he is redirected to his todos#index list .. (users_todos_url)
def after_sign_in_path_for(resource)
....
elsif resource.is_a?(User) && Settings.permit_user_login
stored_location_for(resource) || users_todos_url
....
but then , the error is raised .... and it's stated in the log :
Started GET "/users/todos" for 127.0.0.1 at 2014-07-22 14:29:15 +0200
LoadError - Unable to autoload constant Users::TodosController, expected /Users/yves/bitbucket/railsTests/todoapp/app/controllers/users/todos_controller.rb to define it:
I have a users/todo_controller.rb
class User::TodosController < ApplicationController
..
def index
sort_order = "updated_at DESC , title"
todos = Todo.where(:user_id => current_user[:id]).order(sort_order).page params[:page]
end

Answer 1

Log says todo s _controller.rb.
Controller names are plural form.