ruby on rails: undefined method "version_requirements' when attempting to start server after new install

Question

I had to newly install ruby on rails recently. When I attempted to start the server for a project I had already been working on previous to this new install, I received the following error:

$ ruby script/server
=> Booting WEBrick...
./script/../config/../vendor/rails/railties/lib/rails/gem_dependency.rb:107:in `requirement': undefined method `version_requirements' for #<Gem::Dependency:0xb74bf764> (NoMethodError)
    from ./script/../config/../vendor/rails/railties/lib/initializer.rb:292:in `check_gem_dependencies'
    from ./script/../config/../vendor/rails/railties/lib/initializer.rb:292:in `map'
    from ./script/../config/../vendor/rails/railties/lib/initializer.rb:292:in `check_gem_dependencies'
    from ./script/../config/../vendor/rails/railties/lib/initializer.rb:165:in `process'
from ./script/../config/../vendor/rails/railties/lib/initializer.rb:112:in `send'
    from ./script/../config/../vendor/rails/railties/lib/initializer.rb:112:in `run'
    from /media/78C0-455B/bidmc/schedule/config/environment.rb:13
    from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:36:in `gem_original_require'
    from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:36:in `require'
    from /media/78C0-455B/bidmc/schedule/vendor/rails/activesupport/lib/active_support/dependencies.rb:153:in `require'
    from /media/78C0-455B/bidmc/schedule/vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
    from /media/78C0-455B/bidmc/schedule/vendor/rails/activesupport/lib/active_support/dependencies.rb:153:in `require'
    from /media/78C0-455B/bidmc/schedule/vendor/rails/railties/lib/commands/servers/webrick.rb:59
    from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:36:in `gem_original_require'
    from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:36:in `require'
    from /media/78C0-455B/bidmc/schedule/vendor/rails/activesupport/lib/active_support/dependencies.rb:153:in `require'
    from /media/78C0-455B/bidmc/schedule/vendor/rails/activesupport/lib/active_support/dependencies.rb:521:in `new_constants_in'
    from /media/78C0-455B/bidmc/schedule/vendor/rails/activesupport/lib/active_support/dependencies.rb:153:in `require'
    from /media/78C0-455B/bidmc/schedule/vendor/rails/railties/lib/commands/server.rb:49
    from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:36:in `gem_original_require'
    from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:36:in `require'
    from script/server:3

I have the latest versions of ruby, rubygems, and rails.

Any suggestions?

Thanks.

Solution

Looks like you are using a newer version of rubygems with an older version of rails.

Here's a solution: https://gist.github.com/807008