Ruby on rails 错误：操作控制器：安装bootstrap/custom.css.scss时捕获异常

我被卡住了。。。我正在学习Hartls RoR教程，不知怎的，我无法摆脱一个bug。在第5.1.1节结束之前，一切进展顺利。当我安装bootstrap并设置custom.css.scss时

我只是把我认为你可能需要回答的问题放在这里。不知道更多，希望你能帮我解决这个问题

这是我在本地主机上测试运行它时抛出的结果

ActiveRecord::ConnectionNotEstablished

ActiveRecord::ConnectionNotEstablished

Rails.root: C:/Ruby193/bin/rails_projects/sample_app
Application Trace | Framework Trace | Full Trace

activerecord (3.1.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:409:in `retrieve_connection'
activerecord (3.1.1) lib/active_record/connection_adapters/abstract/connection_specification.rb:107:in `retrieve_connection'
activerecord (3.1.1) lib/active_record/connection_adapters/abstract/connection_specification.rb:89:in `connection'
activerecord (3.1.1) lib/active_record/query_cache.rb:65:in `rescue in call'
activerecord (3.1.1) lib/active_record/query_cache.rb:59:in `call'
activerecord (3.1.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:477:in `call'
actionpack (3.1.1) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
activesupport (3.1.1) lib/active_support/callbacks.rb:392:in `_run_call_callbacks'
activesupport (3.1.1) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.1.1) lib/action_dispatch/middleware/callbacks.rb:28:in `call'
actionpack (3.1.1) lib/action_dispatch/middleware/reloader.rb:68:in `call'
rack (1.3.6) lib/rack/sendfile.rb:101:in `call'
actionpack (3.1.1) lib/action_dispatch/middleware/remote_ip.rb:48:in `call'
actionpack (3.1.1) lib/action_dispatch/middleware/show_exceptions.rb:47:in `call'
railties (3.1.1) lib/rails/rack/logger.rb:13:in `call'
rack (1.3.6) lib/rack/methodoverride.rb:24:in `call'
rack (1.3.6) lib/rack/runtime.rb:17:in `call'
activesupport (3.1.1) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.3.6) lib/rack/lock.rb:15:in `call'
actionpack (3.1.1) lib/action_dispatch/middleware/static.rb:53:in `call'
railties (3.1.1) lib/rails/engine.rb:456:in `call'
railties (3.1.1) lib/rails/rack/content_length.rb:16:in `call'
railties (3.1.1) lib/rails/rack/log_tailer.rb:14:in `call'
rack (1.3.6) lib/rack/handler/webrick.rb:59: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'

Request

Parameters:

None

Show session dump

Show env dump

GATEWAY_INTERFACE: "CGI/1.1"
HTTP_ACCEPT: "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"
HTTP_ACCEPT_ENCODING: "gzip, deflate"
HTTP_ACCEPT_LANGUAGE: "de-de,de;q=0.8,en-us;q=0.5,en;q=0.3"
REMOTE_ADDR: "127.0.0.1"
REMOTE_HOST: XXXXXXXXXXXXX
SERVER_NAME: "localhost"
SERVER_PROTOCOL: "HTTP/1.1"

Response

Headers:

None

这是我的档案：

source 'https://rubygems.org'

gem 'rails', '3.2.6'

# Bundle edge Rails instead:
# gem 'rails', :git => 'git://github.com/rails/rails.git'

gem 'sqlite3'


# Gems used only for assets and not required
# in production environments by default.
group :assets do
  gem 'sass-rails',   '~> 3.2.3'
  gem 'coffee-rails', '~> 3.2.1'

  # See https://github.com/sstephenson/execjs#readme for more supported runtimes
  # gem 'therubyracer', :platforms => :ruby

  gem 'uglifier', '>= 1.0.3'
end

gem 'jquery-rails'

# To use ActiveModel has_secure_password
# gem 'bcrypt-ruby', '~> 3.0.0'

# To use Jbuilder templates for JSON
# gem 'jbuilder'

# Use unicorn as the app server
# gem 'unicorn'

# Deploy with Capistrano
# gem 'capistrano'

# To use debugger
# gem 'debugger'

我尝试了其他gem文件，例如这一个，也不起作用（尽管它在这里回答了另一个问题）：

source 'http://rubygems.org'

gem 'rails', '3.1.1'

gem 'sqlite3'

group :development do
  gem 'rspec-rails', '2.6.1'
end


group :test do
  gem 'rspec-rails', '2.6.1'
  gem 'webrat', '0.7.1'
end

group :assets do
  gem 'sass-rails',   '~> 3.1.4'
  gem 'coffee-rails', '~> 3.1.1'
  gem 'uglifier', '>= 1.0.3'
end

gem 'jquery-rails'