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 methodarity' 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'
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:inblock 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:inload'
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:ineach'
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:inreload!'
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:incall'
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:inupdater'
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:inblock 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:inrun'
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:inblock 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:ineach_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:ineach'
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:ineach_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:intsort_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:ininitialize!'
from /Users/shimizutakuya/taskapp/config/environment.rb:5:in <top (required)>'
from /Users/shimizutakuya/taskapp/config.ru:3:inrequire'
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:ininstance_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:innew'
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:ineval'
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:inparse_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:inapp'
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:inwrapped_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:instart'
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:intap'
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:inrun_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:inrequire'
from bin/rails:4:in `'

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・・・。