start an empty project and see whether you get an error too. Ex:
-> rails tmp
-> cd tmp
-> ruby script/generate rspec
-> ruby script/generate cucumber (look whether it creates all the files)
if not something’s wrong with the gem maybe or …???
In my initial reply, I was trying to say to Christoph (obviously not
very clearly) is that you don't have to manually create the
cucumber.rb file. script/generate cucumber will do that for you.
Can you switch back to Ruby 1.8.7 (or 1.8.6) via RVM or some other
utility and determine if you can run script/generate cucumber without