Shouldn’t have you notice, craigslist-clone is Rails 2.2.

To upgrade to Rails 2.3 (let’s say 2.3.5) you have to do the following:

1. Change RAILS_GEM_VERSION = ‘2.2.2’ unless defined? RAILS_GEM_VERSION in config/environment.rb to RAILS_GEM_VERSION = ‘2.3.5’ unless defined? RAILS_GEM_VERSION

2. run rake rails:update

That’s it

Note: Make sure your application.rb is renamed to application_controller.rb