Errors not logged to the screen in dev mode in 2.3.2

I’ve just upgraded a Rails 2.0.2 app to Rails 2.3.2 to take advantage of
the I18n framework.
I had to change application.rb > application_controller.rb, after that
Mongrel launches.
Still, I have a problem. Even if I launch in development mode, I don’t
see errors logged to the screen, I get the “Something went wrong” page.
Any suggestion?