title: Error while upgrading from Rails 3.2 to Rails 4
body: <p>When upgrading to Rails 4 I encounter the following error:</p>
  
  <pre><code>Bundler could not find compatible versions for gem "railties":
    In Gemfile:
      rails (= 4.0.0) ruby depends on
        railties (= 4.0.0) ruby
  
      sass-rails (~&gt; 4.0.0) ruby depends on
        railties (4.0.0.rc2)
  </code></pre>
  
  <p>My Gemfile looks like this:</p>
  
  <pre><code>source 'https://rubygems.org'
  ruby '2.0.0'
  
  gem 'rails', '4.0.0'
  
  gem 'sass-rails',   '~&gt; 4.0.0'
  gem 'coffee-rails', '~&gt; 4.0.0'
  
  # Other gems
  </code></pre>
  
  <p>Any help would be greatly appreciated.</p>
  
  <p><strong>Update</strong></p>
  
  <p>Entire Gemfile below</p>
  
  <pre><code>source 'https://rubygems.org'
  ruby '2.0.0'
  
  gem 'rails', '4.0.0'
  
  gem 'sass-rails',   '~&gt; 4.0.0'
  gem 'coffee-rails', '~&gt; 4.0.0'
  gem 'less', '~&gt; 2.3.1'
  gem 'uglifier', '&gt;= 1.0.3'
  gem 'therubyracer', '0.11.0', platforms: :ruby
  gem 'less-rails-fontawesome', '~&gt; 0.4.0'
  gem 'hogan_assets', '~&gt; 1.5.1'
  gem 'datejs-rails', '~&gt; 2.0.1'
  gem 'flot-rails', '~&gt; 0.0.3'
  
  gem 'jquery-rails', '~&gt; 2.1.2'
  gem 'jquery-ui-rails', '~&gt; 4.0.3'
  gem 'pg', '~&gt; 0.14.1'
  gem 'pg_search', '~&gt; 0.5.7'
  gem 'devise', '~&gt; 2.2.4'
  gem 'cancan', '~&gt; 1.6.9'
  gem 'slim-rails', '~&gt; 1.1.0'
  gem 'less-rails-bootstrap', '~&gt; 2.3.2'
  gem 'rmagick', '~&gt; 2.13.1'
  gem 'mime-types', '~&gt; 1.19'
  gem 'carrierwave', '~&gt; 0.7.1'
  gem 'kaminari', '~&gt; 0.14.1'
  gem 'carmen-rails', git: 'git://github.com/jim/carmen-rails.git'
  gem 'pacecar', '~&gt; 1.5.3'
  gem 'ancestry', '~&gt; 1.3.0'
  gem 'acts-as-taggable-on', '~&gt; 2.3.3'
  gem 'state_machine', '~&gt; 1.1.2'
  gem 'dynamic_form', '~&gt; 1.1.4'
  gem 'simple_form', '~&gt; 2.1.0'
  gem 'rdiscount', '~&gt; 1.6.8'
  gem 'nokogiri', '~&gt; 1.5.6'
  gem 'htmlentities', '~&gt; 4.3.1'
  gem 'bootstrap-wysihtml5-rails', '~&gt; 0.3.1.14'
  gem 'settingslogic', '~&gt; 2.0.9'
  gem 'simple-navigation', '~&gt; 3.9.0'
  gem 'range_validator', '~&gt; 0.2.1'
  gem 'valid_email', '~&gt; 0.0.4'
  gem 'ransack', '~&gt; 0.7.2'
  gem 'mongoid', '~&gt; 3.1.3'
  gem 'bson_ext', '~&gt; 1.8.2'
  gem 'rails3-jquery-autocomplete', '~&gt; 1.0.10'
  gem 'validates_timeliness', '~&gt; 3.0'
  gem 'time_diff', '~&gt; 0.3.0'
  gem 'responders', '~&gt; 0.9.3'
  gem 'tenacity', '~&gt; 0.6.0'
  gem 'puma', '~&gt; 1.6.3'
  gem 'redis', '~&gt; 3.0.2'
  gem 'country_select', '~&gt; 1.1.3'
  gem 'sidekiq', '~&gt; 2.7.5'
  gem 'action_presenter', '~&gt; 1.1.6'
  gem 'bootstrap-datetimepicker-rails', '~&gt; 0.0.10'
  
  group :development do
    gem 'bullet', '~&gt; 4.3.0'
    gem 'uniform_notifier', '~&gt; 1.1.1'
    gem 'battlestation', '~&gt; 0.0.3'
    gem 'libv8', '3.11.8.4', platform: :ruby
    gem 'foreman', '~&gt; 0.61.0'
    gem 'better_errors', '~&gt; 0.3.2'
    gem 'binding_of_caller', '~&gt; 0.7.1'
    gem 'meta_request', '~&gt; 0.2.1'
  end
  
  group :development, :test do
    gem 'rspec-rails', '~&gt; 2.13.0'
    gem 'fakeweb', '~&gt; 1.3.0'
    gem 'timecop', '~&gt; 0.5.7'
    gem 'quiet_assets', '~&gt; 1.0.1'
    gem 'forgery', '~&gt; 0.5.0'
    gem 'seedbank', '~&gt; 0.2.0'
    gem 'factory_girl_rails', '~&gt; 4.1.0'
    gem 'mongoid-rspec', '~&gt; 1.5.6'
  end
  
  group :test do
    gem 'capybara', '~&gt; 2.0.2'
    gem 'capybara-webkit', '~&gt; 0.14.1'
    gem 'launchy', '~&gt; 2.2.0'
    gem 'shoulda-matchers', '~&gt; 2.0.0'
    gem 'database_cleaner', '~&gt; 0.9.1'
    gem 'rspec-html-matchers', '~&gt; 0.4.0'
  end
  </code></pre>