title: Rails 3.1.2 - Bundler could not find compatible versions for gem "railties"
body: <p>I am trying to install the new version of the <code>twitter-bootstrap-rails</code> gem (v2), but getting the error above. This is how my Gemfile looks:</p>
  
  <pre><code>source 'http://rubygems.org'
  
  gem 'rails', '3.1.2'
  
  # Bundle edge Rails instead:
  # gem 'rails',     :git =&gt; 'git://github.com/rails/rails.git'
  
  
  gem 'mysql2'
  gem 'authlogic'
  gem "paperclip", "~&gt; 2.4.5"
  gem 'aws-s3'
  gem 'actionmailer'
  gem "twitter-bootstrap-rails", "~&gt; 2.0"
  gem 'sunspot_rails'
  
  #endless page
  gem 'will_paginate'
  
  # Gems used only for assets and not required
  # in production environments by default.
  group :assets do
    gem 'sass-rails',   '~&gt; 3.1.5.rc.2'
    gem 'coffee-rails', '~&gt; 3.1.1'
    gem 'uglifier', '&gt;= 1.0.3'
  end
  
  group :production do
    gem 'therubyracer-heroku', '~&gt; 0.8.1.pre3'
    gem 'pg'
    gem 'thin'
  end
  
  group :development do
    gem "taps", "~&gt; 0.3.23"
    gem "rvm", "~&gt; 1.9.2"
  end
  
  gem 'jquery-rails'
  
  # To use ActiveModel has_secure_password
  # gem 'bcrypt-ruby', '~&gt; 3.0.0'
  
  # Use unicorn as the web server
  # gem 'unicorn'
  
  # Deploy with Capistrano
  # gem 'capistrano'
  
  # To use debugger
  # gem 'ruby-debug19', :require =&gt; 'ruby-debug'
  </code></pre>
  
  <p>And complete error:</p>
  
  <pre><code>Bundler could not find compatible versions for gem "railties":
    In Gemfile:
      twitter-bootstrap-rails (~&gt; 2.0) ruby depends on
        railties (&gt;= 3.2.1) ruby
  
      sass-rails (~&gt; 3.1.5.rc.2) ruby depends on
        railties (3.1.0)
  </code></pre>
  
  <p>What is wrong? When I remove the version <code>~&gt; 2.0</code> from the gem, it works, but I need the new version of bootstrap...</p>
  
  <p><strong>EDIT:</strong> bundle install</p>
  
  <pre><code>Bundler could not find compatible versions for gem "railties":
    In snapshot (Gemfile.lock):
      railties (3.1.2)
  
    In Gemfile:
      twitter-bootstrap-rails (~&gt; 2.0) ruby depends on
        railties (&gt;= 3.2.1) ruby
  
  Running `bundle update` will rebuild your snapshot from scratch, using only
  the gems in your Gemfile, which may resolve the conflict.
  </code></pre>