How to Upgrade Your Rails App? Jan 19th, 2015 10:50 am updating the Rails version in the Gemfile and run this rake task. 1 2 3 4 5 # Gemfile # Bundle edge Rails instead: gem 'rails', github: 'rails/rails' gem 'rails', '4.x.x' # <- updating the version of rails info $ rake rails:update done. http://edgeguides.rubyonrails.org/upgrading_ruby_on_rails.html