我正在将我的应用程序从 Rails 3.2 升级到 Rails 4，并在尝试启动正在开发的服务器时遇到此错误。关于如何解决这个问题的任何想法？
/Users/timkleier/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-4.0.0/lib/active_support/dependencies/autoload.rb:1:in `require': /Users/timkleier/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-4.0.0/lib/active_support/inflector/methods.rb:128: undefined (?...) sequence: /\b(?<!['\342\200\231`])[a-z]/ (SyntaxError)
from /Users/timkleier/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-4.0.0/lib/active_support/dependencies/autoload.rb:1
from /Users/timkleier/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-4.0.0/lib/active_support.rb:25:in `require'
from /Users/timkleier/.rvm/gems/ruby-2.0.0-p247/gems/activesupport-4.0.0/lib/active_support.rb:25
from /Users/timkleier/.rvm/gems/ruby-2.0.0-p247/gems/actionpack-4.0.0/lib/action_dispatch.rb:24:in `require'
from /Users/timkleier/.rvm/gems/ruby-2.0.0-p247/gems/actionpack-4.0.0/lib/action_dispatch.rb:24
from /Users/timkleier/.rvm/gems/ruby-2.0.0-p247/gems/railties-4.0.0/lib/rails/commands/server.rb:3:in `require'
from /Users/timkleier/.rvm/gems/ruby-2.0.0-p247/gems/railties-4.0.0/lib/rails/commands/server.rb:3
from /Users/timkleier/.rvm/gems/ruby-2.0.0-p247/gems/railties-4.0.0/lib/rails/commands.rb:72:in `require'
from /Users/timkleier/.rvm/gems/ruby-2.0.0-p247/gems/railties-4.0.0/lib/rails/commands.rb:72
from script/rails:6:in `require'
from script/rails:6
这是我的 Gemfile 和相关的宝石：
source 'http://rubygems.org'
gem 'rails', '4.0.0'
gem 'activerecord'
gem 'execjs'
gem 'therubyracer'
gem "composite_primary_keys", :git => 'git://github.com/drnic/composite_primary_keys.git', :branch => 'ar_4.0.x'
gem "tiny_tds", "~> 0.5.1"
gem 'twitter-bootstrap-rails'
gem "less-rails"
gem 'sass-rails', '4.0.0'
gem 'uglifier', '2.1.1'
gem 'coffee-rails', '4.0.0'
gem 'jquery-rails', '2.2.1'
在 config/application.rb 中，我已经根据这篇文章注释掉了 Active Resource ，但它似乎无关紧要。