http://www.hollandonrails.nl/articles/516-Upgrading-to-rails-3-0 Seeing as upgrading your <3.0 rails app isn't just changing the rails version in your env.rb I started looking for an easier way. Scouring through the internet, I stumbled across this little gem + guide: <a href="http://omgbloglol.com/post/359147788/rails-upgrade-automating-a-portion-of-the-rails-3">rails-upgrade-automating-a-portion-of-the-rails-3</a> by Jeremy McAnally. I haven't found time to play with it much, but I'll definitely look into it more this weekend. He also wrote a book <a href="http://www.railsupgradehandbook.com/?r=rubyinside">railsupgradehandbook</a> that gives you the basic tips / tricks to upgrade your app to a rails 3.0 app.