我尝试重新安装我的rails并删除我的.rbenv并再次安装。这些方法都不起作用。我使用的是rails 4.2.1。
这是＆＃34; rails服务器启动时遇到的错误＆＃34;：
/Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:274:in `require': cannot load such file -- rack/handler/start (LoadError)
from /Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:274:in `block in require'
from /Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:240:in `load_dependency'
from /Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/activesupport-4.2.1/lib/active_support/dependencies.rb:274:in `require'
from /Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.4/lib/rack/handler.rb:78:in `try_require'
from /Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.4/lib/rack/handler.rb:16:in `get'
from /Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.4/lib/rack/server.rb:290:in `server'
from /Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/commands/server.rb:125:in `print_boot_information'
from /Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/commands/server.rb:75:in `start'
from /Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/commands/commands_tasks.rb:80:in `block in server'
from /Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/commands/commands_tasks.rb:75:in `tap'
from /Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/commands/commands_tasks.rb:75:in `server'
from /Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
from /Users/CQ/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/commands.rb:17:in `<top (required)>'
from bin/rails:8:in `require'
from bin/rails:8:in `<main>'
答案 0 :(得分：1)
该命令仅为rails server或rails s。
请参阅：http://guides.rubyonrails.org/command_line.html#rails-server