No route matches [GET] "/reporting/from_perl/0" after upgrading to Rails 3.1

I'm upgrading a very old rails application step by step. At the moment I am stuck at Rails 3.1. I did all the relevant steps for upgrading. For now I don't want to use assets so I disabled it in config/application.rb.

As soon as a change the rails version in my Gemfile from 3.0.20 to 3.1.12 I get a no-route-matches error. I also changed all upgrading steps back to 3.0 to see which part causes the error but it happens only when I change the line in the Gemfile.

My routes.rb:

Wawi::Application.routes.draw do
match ":controller(/:action(/:id(.:format)))"
end

Please tell me if you need more code.