Ruby on rails “云9轨道”；这里似乎没有运行任何应用程序”；运行时错误

我正在使用Cloud9开发一个简单的Rails应用程序

每次运行应用程序时，我都会在Cloud 9浏览器中遇到此错误

No application seems to be running here!

我研究过这个，但我不知道为什么。我曾经

rails s -b $IP -p $PORT

启动服务器。这是在应用程序的根目录中完成的。我已经安装了所需的所有Rails gems/bundle

当我运行应用程序时，终端会显示一条消息

my code is running at htttps://......... example

当我点击链接时，就是我看到错误的时候

这是我尝试启动服务器后终端的响应：

$ rails server –b $IP –p $PORT

Exiting
/usr/local/rvm/gems/ruby-2.3.0/gems/rack-1.6.4/lib/rack/handler.rb:78:in `require': cannot load such file -- rack/handler/–b (LoadError)
        from /usr/local/rvm/gems/ruby-2.3.0/gems/rack-1.6.4/lib/rack/handler.rb:78:in `try_require'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/rack-1.6.4/lib/rack/handler.rb:16:in `get'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/rack-1.6.4/lib/rack/server.rb:290:in `server'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/server.rb:125:in `print_boot_information'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/server.rb:75:in `start'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/commands_tasks.rb:80:in `block in server'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/commands_tasks.rb:75:in `tap'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/commands_tasks.rb:75:in `server'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands.rb:17:in `<top (required)>'
        from /home/ubuntu/workspace/dublinapp/bin/rails:9:in `require'
        from /home/ubuntu/workspace/dublinapp/bin/rails:9:in `<top (required)>'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/client/rails.rb:28:in `load'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/client/rails.rb:28:in `call'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/client/command.rb:7:in `call'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/client.rb:28:in `run'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/bin/spring:49:in `<top (required)>'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/binstub.rb:11:in `load'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/binstub.rb:11:in `<top (required)>'
        from /home/ubuntu/workspace/dublinapp/bin/spring:13:in `require'
        from /home/ubuntu/workspace/dublinapp/bin/spring:13:in `<top (required)>'
        from bin/rails:3:in `load'
        from bin/rails:3:in `<main>'

$rails服务器–b$IP–p$PORT
退出
/usr/local/rvm/gems/ruby-2.3.0/gems/rack-1.6.4/lib/rack/handler.rb:78:在“require”中：无法加载这样的文件--rack/handler/-b（LoadError）
from/usr/local/rvm/gems/ruby-2.3.0/gems/rack-1.6.4/lib/rack/handler.rb:78:in'try_require'
from/usr/local/rvm/gems/ruby-2.3.0/gems/rack-1.6.4/lib/rack/handler.rb:16:in'get'
from/usr/local/rvm/gems/ruby-2.3.0/gems/rack-1.6.4/lib/rack/server.rb:290:in'server'
从/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/server.rb:125:“打印启动信息”中
from/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/server.rb:75:in'start'
from/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/commands\u tasks.rb:80:in“服务器中的块”
from/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/commands\u tasks.rb:75:in'tap'
from/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/commands_tasks.rb:75:在“服务器”中
from/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands/commands\u tasks.rb:39:in“run\u command！”
from/usr/local/rvm/gems/ruby-2.3.0/gems/railties-4.2.6/lib/rails/commands.rb:17:in`'
from/home/ubuntu/workspace/dublinapp/bin/rails:9:in'require'
from/home/ubuntu/workspace/dublinapp/bin/rails:9:in`'
from/usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/client/rails.rb:28:in'load'
from/usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/client/rails.rb:28:in'call'
from/usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/client/command.rb:7:in'call'
from/usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/client.rb:28:in'run'
from/usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/bin/spring:49:in`'
from/usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/binstub.rb:11:in'load'
from/usr/local/rvm/gems/ruby-2.3.0/gems/spring-1.6.4/lib/spring/binstub.rb:11:in`'
from/home/ubuntu/workspace/dublinapp/bin/spring:13:in'require'
from/home/ubuntu/workspace/dublinapp/bin/spring:13:in`'
来自料仓/轨道：3:在“装载”中
从箱子/轨道：3:in`'

尝试删除Gemfile.lock和bundle安装，然后双击rails s-b$IP-p$port，因为另一个进程已经连接到端口8080。尝试或张贴在，你会得到帮助。