Error with sass-rails gem when trying to run rails server

Question

I am using ruby 2.3.0, and rails 4.2.0. when I try to run rails server, I am getting error that seems to be related to sass-rails gem. I am not sure why this isn't working.

Thank You

here is the error:

roman@quotebeam:~/workspace/hello_app$ rails server /home/roman/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/bundler-1.11.2/lib/bundler/runtime.rb:80:in rescue in block (2 levels) in require': There was an error while trying to load the gem 'sass-rails'. (Bundler::GemRequireError) from /home/roman/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/bundler-1.11.2/lib/bundler/runtime.rb:76:inblock (2 levels) in require'

here is my gemfile

source 'https://rubygems.org'

gem 'rails', '4.2.0'

gem 'sass-rails', '5.0.1'

gem 'uglifier', '2.5.3'

gem 'coffee-rails', '4.1.0'

gem 'jquery-rails', '4.0.3'

gem 'turbolinks', '2.3.0'

gem 'jbuilder', '2.2.3'

gem 'sdoc', '0.4.0', group: :doc

group :development, :test do

gem 'sqlite3', '1.3.9'

gem 'byebug', '3.4.0'

gem 'web-console', '~> 2.0'

gem 'spring', '1.1.3'

end