rails sで、いつも通り立ち上がらないです。

#rails sすると・・・

学習していたのはドットインストールの『Ruby on Rails 4入門』の、レッスン20『Tasksの設定をしていこう』です。→http://dotinstall.com/lessons/basic_rails_v2/24920

順調に進んでいたのですが、途中で異変が。

rails sするとこんな感じで立ち上がらない。

>=> Booting WEBrick
=> Rails 4.1.0 application starting in development on http://0.0.0.0:3000
=> Run `rails server -h` for more startup options
=> Notice: server is listening on all interfaces (0.0.0.0). Consider using 127.0.0.1 (--binding option)
=> Ctrl-C to shutdown server
Exiting
/Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/actionpack-4.1.0/lib/action_dispatch/routing/route_set.rb:327:in `eval_block': undefined method `arity' for nil:NilClass (NoMethodError)
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/actionpack-4.1.0/lib/action_dispatch/routing/route_set.rb:313:in `draw'
	from /Users/shimizutakuya/taskapp/config/routes.rb:1:in `<top (required)>'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:241:in `load'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:241:in `block in load'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:232:in `load_dependency'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/activesupport-4.1.0/lib/active_support/dependencies.rb:241:in `load'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/application/routes_reloader.rb:40:in `block in load_paths'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/application/routes_reloader.rb:40:in `each'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/application/routes_reloader.rb:40:in `load_paths'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/application/routes_reloader.rb:16:in `reload!'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/application/routes_reloader.rb:26:in `block in updater'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/activesupport-4.1.0/lib/active_support/file_update_checker.rb:75:in `call'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/activesupport-4.1.0/lib/active_support/file_update_checker.rb:75:in `execute'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/application/routes_reloader.rb:27:in `updater'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/application/routes_reloader.rb:7:in `execute_if_updated'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/application/finisher.rb:71:in `block in <module:Finisher>'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/initializable.rb:30:in `instance_exec'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/initializable.rb:30:in `run'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/initializable.rb:55:in `block in run_initializers'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/2.1.0/tsort.rb:226:in `block in tsort_each'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/2.1.0/tsort.rb:348:in `block (2 levels) in each_strongly_connected_component'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/2.1.0/tsort.rb:427:in `each_strongly_connected_component_from'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/2.1.0/tsort.rb:347:in `block in each_strongly_connected_component'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/2.1.0/tsort.rb:345:in `each'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/2.1.0/tsort.rb:345:in `call'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/2.1.0/tsort.rb:345:in `each_strongly_connected_component'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/2.1.0/tsort.rb:224:in `tsort_each'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/2.1.0/tsort.rb:205:in `tsort_each'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/initializable.rb:54:in `run_initializers'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/application.rb:288:in `initialize!'
	from /Users/shimizutakuya/taskapp/config/environment.rb:5:in `<top (required)>'
	from /Users/shimizutakuya/taskapp/config.ru:3:in `require'
	from /Users/shimizutakuya/taskapp/config.ru:3:in `block in <main>'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:55:in `instance_eval'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:55:in `initialize'
	from /Users/shimizutakuya/taskapp/config.ru:in `new'
	from /Users/shimizutakuya/taskapp/config.ru:in `<main>'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:49:in `eval'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:49:in `new_from_string'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:40:in `parse_file'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/server.rb:277:in `build_app_and_options_from_config'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/server.rb:199:in `app'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/commands/server.rb:50:in `app'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/rack-1.5.2/lib/rack/server.rb:314:in `wrapped_app'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/commands/server.rb:130:in `log_to_stdout'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/commands/server.rb:67:in `start'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/commands/commands_tasks.rb:81:in `block in server'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/commands/commands_tasks.rb:76:in `tap'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/commands/commands_tasks.rb:76:in `server'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/commands/commands_tasks.rb:40:in `run_command!'
	from /Users/shimizutakuya/.rbenv/versions/2.1.0/lib/ruby/gems/2.1.0/gems/railties-4.1.0/lib/rails/commands.rb:17:in `<top (required)>'
	from bin/rails:4:in `require'
	from bin/rails:4:in `<main>'
>

#参考になりそうなサイトは・・・

binの場所が変わったことが原因？
http://u16suzu.hatenablog.com/entry/20130414/1365935728

しかし、これも試すもrails sで立ち上がらず。

pidファイルを消す？
http://qiita.com/pakiran/items/53c42257ab3f95907ab8

しかし、これでもうまくいかず。

どなたかお知恵をお貸しくださいませ・・・。