Setting root path: wrong number of arguments(1 for 0) - ruby-on-rails

Question

I appreciate that this is a very common error in Ruby. I've just started learning Ruby on Rails but I've gathered that this basically comes from passing the wrong number of arguments to a method.
I was reading through the Ruby docs and it seems that the standard way to have your root path is to have a PagesController with a main view. In "routes.rb" I have:
root to: 'pages#main'
This is my PagesController:
class PagesController < ApplicationController
def main
end
end
From my understanding, main is the default route, which I am trying to access. I have a main method which doesn't take any parameters but somehow it is being passed one. Where am I going wrong here?
Errors:
ArgumentError in PagesController#main
wrong number of arguments(1 for 0)
Rails.root: C:/RubymineProjects/ShoppingApp
Full Trace:
actionpack (4.0.1) lib/abstract_controller/base.rb:89:in `initialize'
actionpack (4.0.1) lib/abstract_controller/base.rb:89:in `new'
actionpack (4.0.1) lib/abstract_controller/base.rb:89:in `action_methods'
actionpack (4.0.1) lib/action_controller/metal/hide_actions.rb:36:in `action_methods'
actionpack (4.0.1) lib/abstract_controller/url_for.rb:25:in `action_methods'
actionpack (4.0.1) lib/abstract_controller/base.rb:179:in `action_method?'
actionpack (4.0.1) lib/abstract_controller/base.rb:230:in `method_for_action'
actionpack (4.0.1) lib/action_controller/metal/hide_actions.rb:17:in `method_for_action'
actionpack (4.0.1) lib/action_controller/metal/implicit_render.rb:14:in `method_for_action'
actionpack (4.0.1) lib/abstract_controller/base.rb:130:in `process'
actionpack (4.0.1) lib/abstract_controller/rendering.rb:44:in `process'
actionpack (4.0.1) lib/action_controller/metal.rb:195:in `dispatch'
actionpack (4.0.1) lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
actionpack (4.0.1) lib/action_controller/metal.rb:231:in `block in action'
actionpack (4.0.1) lib/action_dispatch/routing/route_set.rb:80:in `call'
actionpack (4.0.1) lib/action_dispatch/routing/route_set.rb:80:in `dispatch'
actionpack (4.0.1) lib/action_dispatch/routing/route_set.rb:48:in `call'
actionpack (4.0.1) lib/action_dispatch/journey/router.rb:71:in `block in call'
actionpack (4.0.1) lib/action_dispatch/journey/router.rb:59:in `each'
actionpack (4.0.1) lib/action_dispatch/journey/router.rb:59:in `call'
actionpack (4.0.1) lib/action_dispatch/routing/route_set.rb:680:in `call'
rack (1.5.2) lib/rack/etag.rb:23:in `call'
rack (1.5.2) lib/rack/conditionalget.rb:25:in `call'
rack (1.5.2) lib/rack/head.rb:11:in `call'
actionpack (4.0.1) lib/action_dispatch/middleware/params_parser.rb:27:in `call'
actionpack (4.0.1) lib/action_dispatch/middleware/flash.rb:241:in `call'
rack (1.5.2) lib/rack/session/abstract/id.rb:225:in `context'
rack (1.5.2) lib/rack/session/abstract/id.rb:220:in `call'
actionpack (4.0.1) lib/action_dispatch/middleware/cookies.rb:486:in `call'
activerecord (4.0.1) lib/active_record/query_cache.rb:36:in `call'
activerecord (4.0.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:626:in `call'
activerecord (4.0.1) lib/active_record/migration.rb:369:in `call'
actionpack (4.0.1) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (4.0.1) lib/active_support/callbacks.rb:373:in `_run__897547547__call__callbacks'
activesupport (4.0.1) lib/active_support/callbacks.rb:80:in `run_callbacks'
actionpack (4.0.1) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (4.0.1) lib/action_dispatch/middleware/reloader.rb:64:in `call'
actionpack (4.0.1) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
actionpack (4.0.1) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
actionpack (4.0.1) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.0.1) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.0.1) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.0.1) lib/active_support/tagged_logging.rb:67:in `block in tagged'
activesupport (4.0.1) lib/active_support/tagged_logging.rb:25:in `tagged'
activesupport (4.0.1) lib/active_support/tagged_logging.rb:67:in `tagged'
railties (4.0.1) lib/rails/rack/logger.rb:20:in `call'
actionpack (4.0.1) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
rack (1.5.2) lib/rack/runtime.rb:17:in `call'
activesupport (4.0.1) lib/active_support/cache/strategy/local_cache.rb:83:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
actionpack (4.0.1) lib/action_dispatch/middleware/static.rb:64:in `call'
rack (1.5.2) lib/rack/sendfile.rb:112:in `call'
railties (4.0.1) lib/rails/engine.rb:511:in `call'
railties (4.0.1) lib/rails/application.rb:97:in `call'
rack (1.5.2) lib/rack/lock.rb:17:in `call'
rack (1.5.2) lib/rack/content_length.rb:14:in `call'
rack (1.5.2) lib/rack/handler/webrick.rb:60:in `service'
C:/Ruby193/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
C:/Ruby193/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
C:/Ruby193/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'

Answer 1

does
root 'pages#main'
solve the problem? (In rails 4, the documentations don't mention a "to:")

Answer 2

I had the same issue.
Except for me I was using a rails word that I shouldn't have been using.
In my routes.rb file:
root :to => 'static#main'
and I got the same error as you.
in static_controller.rb I had
class StaticController < ApplicationController
def main
end
def blog
end
def about
end
def process
end
end
the problem was the method named process. I changed it to myprocess and everything worked.
Rails is like your significant other. Really annoying and frustrating when there's something wrong but they won't tell you what, but incredibly awesome and fantastic when everything goes the way it should.