Upgrading Ruby on Rails application from 1.2.3 to 2.0.2

Upgrading an existing Ruby on Rails application from 1.2.3, to 2.0.2, presents few problems. I will try and keep a record of the ones I encounter along the way, here.


  1. Change the config/environment.rb to let the application know to use the 2.0.2 gem rail version,
  2. change the following line from:

    RAILS_GEM_VERSION = '1.2.3' unless defined? RAILS_GEM_VERSION


    RAILS_GEM_VERSION = "2.0.2" unless defined? RAILS_GEM_VERSION
  3. Run the following to generate the secret key for the application:
  4. rake secret
  5. Copy the magic key in a new section in your config/environment.rb as in:
  6. ...
        # config.log_level = :debug
        # Your secret key for verifying cookie session data integrity.
        # If you change this key, all old sessions will become invalid!
        # Make sure the secret is at least 30 characters and all random,
        # no regular words or you'll be exposed to dictionary attacks.
        config.action_controller.session = {
          :session_key => '_yourapplication_session',
          :secret      => 'long_string_generated_from_rake_secret'