I have recently upgraded to Rails 3 and created a new application with Rails 3.0.3, but I keep getting an error
Macintosh:$ rails server => Booting WEBrick => Rai
If you're seeing this recently, it's because mysql2 0.3 removed the ActiveRecord Adapter, which is now part of Rails 3.1
WARNING: This version of mysql2 (0.3.2) doesn't ship with the ActiveRecord adapter bundled anymore as it's now part of Rails 3.1
WARNING: Please use the 0.2.x releases if you plan on using it in Rails <= 3.0.x
Adjust your Gemfile accordingly if you're on Rails 3.0.x
gem 'mysql2', '~> 0.2.6'