我在http://ruby.railstutorial.org/chapters/static-pages#fig-green_passing_spec关注 RailsTutorial，运行时收到错误消息：
bundle exec rspec spec/requests/static_pages_spec.rb
我得到以下输出：
Rack::File headers parameter replaces cache_control after Rack 1.5.
B:/rails_projects/sample_app/app/controllers/application_controller.rb:1:in `<top (required)>': uninitialized constant ApplicationController (NameError)
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/engine.rb:439:in `block (2 levels) in eager_load!'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/engine.rb:438:in `each'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/engine.rb:438:in `block in eager_load!'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/engine.rb:436:in `each'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/engine.rb:436:in `eager_load!'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/application/finisher.rb:53:in `block in <module:Finisher>'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/initializable.rb:30:in `instance_exec'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/initializable.rb:30:in `run'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/initializable.rb:55:in `block in run_initializers'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/initializable.rb:54:in `each'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/initializable.rb:54:in `run_initializers'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/application.rb:136:in `initialize!'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-3.2.11/lib/rails/railtie/configurable.rb:30:in `method_missing'
from B:/rails_projects/sample_app/config/environment.rb:5:in `<top (required)>'
from B:/rails_projects/sample_app/spec/spec_helper.rb:3:in `require'
from B:/rails_projects/sample_app/spec/spec_helper.rb:3:in `<top (required)>'
from B:/rails_projects/sample_app/spec/requests/static_pages_spec.rb:1:in `require'
from B:/rails_projects/sample_app/spec/requests/static_pages_spec.rb:1:in `<top (required)>'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/rspec-core-2.11.1/lib/rspec/core/configuration.rb:780:in `load'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/rspec-core-2.11.1/lib/rspec/core/configuration.rb:780:in `block in load_spec_files'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/rspec-core-2.11.1/lib/rspec/core/configuration.rb:780:in `map'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/rspec-core-2.11.1/lib/rspec/core/configuration.rb:780:in `load_spec_files'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/rspec-core-2.11.1/lib/rspec/core/command_line.rb:22:in `run'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/rspec-core-2.11.1/lib/rspec/core/runner.rb:69:in `run'
from B:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/rspec-core-2.11.1/lib/rspec/core/runner.rb:8:in `block in autorun'
这是我正在使用的gemfile：
source 'https://rubygems.org'
gem 'rails', '3.2.11'
group :development, :test do
gem 'sqlite3', '1.3.5'
gem 'rspec-rails', '2.11.0'
end
# Gems used only for assets and not required
# in production environments by default.
group :assets do
gem 'sass-rails', '3.2.5'
gem 'coffee-rails', '3.2.2'
gem 'uglifier', '1.2.3'
end
gem 'jquery-rails', '2.0.2'
group :test do
gem 'capybara', '1.1.2'
end
group :production do
gem 'pg', '0.12.2'
end
我一个月前完成了第 3 章，没有任何问题。从那时到现在，唯一的变化是由于暴露的漏洞而对 Rails 进行了更新。
知道我做错了什么，或者我应该改变/看看什么？