尝试使Rails服务器在Windows命令提示符下运行时出错

Question

I've been developing a (very simple) Rails project and have moved the files to a new machine. I have Ruby (version 2.0.0p195) and Rails (4.0.0) installed. From the C:\\Sites directory in command prompt (console), when I type 'rails server' I get a whole bunch of information that starts with:

Usage:
rails new APP_PATH [options]
...

...and continues with Options:, Runtime options:, Rails options: and so on.
When I cd to the directory of my copied project:
C:\\Sites\\elearning
and try 'rails server' I get the following error:

'mri_21' is not a valid platform. The available options are: [:ruby, :ruby_18, :ruby_19, :ruby_20, :mri, :mri_18, :mri_19, :mri_20, :rbx, :jruby, :mswim, :mingw, :mingw_18, :mingw_19, :mingw_20]

Does anyone know what I'm doing wrong? Is it possible to copy a rails project from another computer? And if so, how would I do that?

Any help, much appreciated.

Edit:

FYI, my gemfile is as follows:

source 'https://rubygems.org'
ruby '2.1.2'
gem 'rails', '4.1.5'
gem 'sass-rails', '~> 4.0.3'
gem 'uglifier', '>= 1.3.0'
gem 'coffee-rails', '~> 4.0.0'
gem 'jquery-rails'
gem 'turbolinks'
gem 'jbuilder', '~> 2.0'
gem 'sdoc', '~> 0.4.0',          group: :doc
gem 'spring',        group: :development
gem 'bootstrap-sass'
gem 'devise'
gem 'sqlite3'
gem 'thin'
group :development do
  gem 'better_errors'
  gem 'binding_of_caller', :platforms=>[:mri_21]
  gem 'quiet_assets'
  gem 'rails_layout'
  gem 'byebug'
end

Answer 1

For those trying to transfer a mac project to PC: I've finally got rails server running.

First, in the gem file, I changed the reference 'mri_21' to 'mri_20' and changed the ruby version number to match my version of ruby.

I had other errors, but the short story is that I created a new rails project, copied MOST of the old project files into the corresponding files of the new project and EVENTUALLY noticed the comment at the bottom of the new (freshly created) routes.rb file:

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem

So I added:

gem 'tzinfo-data', platforms: [:mingw, :mswin]

and all is, for now, right with the world.

So, if you're transferring a mac project to PC, you'll need to add the tzinfo-data gem to your gemfile.

Answer 2

尝试运行“ gem更新捆绑程序”，看看是否可行。