最近我将rails 4.0升级到4.1，创建新的应用程序工作很好，但是在运行另一个现有应用程序时，它会抛出错误。
使用＆＃34; rails new appname＆＃34;生成应用程序后工作正常，错误来自olders one（4.0 old）
rails server
/usr/local/lib/ruby/gems/2.1.0/gems/bundler-1.6.2/lib/bundler/runtime.rb:34:in `block in setup': You have already activated sprockets 2.12.1, but your Gemfile requires sprockets 2.11.0. Prepending `bundle exec` to your command may solve this. (Gem::LoadError) from /usr/local/lib/ruby/gems/2.1.0/gems/bundler-1.6.2/lib/bundler/runtime.rb:19:in `setup'
from /usr/local/lib/ruby/gems/2.1.0/gems/bundler-1.6.2/lib/bundler.rb:127:in `setup'
from /usr/local/lib/ruby/gems/2.1.0/gems/bundler-1.6.2/lib/bundler.rb:132:in `require'
from /home/lazaro/ejemplo/config/application.rb:8:in `<top (required)>'
from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:126:in `require'
from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:126:in `require'
from /usr/local/lib/ruby/gems/2.1.0/gems/railties-4.1.1/lib/rails/commands/commands_tasks.rb:146:in `require_application_and_environment!'
from /usr/local/lib/ruby/gems/2.1.0/gems/railties-4.1.1/lib/rails/commands/commands_tasks.rb:68:in `console'
from /usr/local/lib/ruby/gems/2.1.0/gems/railties-4.1.1/lib/rails/commands/commands_tasks.rb:40:in `run_command!'
from /usr/local/lib/ruby/gems/2.1.0/gems/railties-4.1.1/lib/rails/commands.rb:17:in `<top (required)>'
from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:135:in `require'
from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:135:in `rescue in require'
from /usr/local/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:144:in `require'
from bin/rails:4:in `<main>'