I was having trouble with the error message:

undefined method `^' for etc

whilst running the Recipe editor in Ch.1 (I hadn't made it past p.22 really)
so I spent some time searching and found that it is a Rails 2.3.4 bug that is documented here .

I'm not that pro to understand what anyone at lighthouse was talking about, but I did copy the patch provided. Of course those folks are speaking among fellow rails nerds who do not need instructions for applying patches. Another option would be to downgrade to a more stable version, rails 2.3.2 perhaps. I found some instructions for this exact patch problem at this blog which didn't work for me. Finally I just located and edited the ruby/gems/1.9.1/gems/activesupport-2.3.4/lib/active_support/message_verifier.rb file and manually altered it to reflect the changes in the patch, restarted my server and Voila! It worked.

So, until the delayed Rails 2.3.5 is available, I would suggest anyone running 2.3.4 with ruby 1.9+ look into this issue and consider your options. Diagnostics: the view (in this case /recipes/new) loads fine the first time, but after that, the weird errors appear (involving undefined method `^' ). Check this by deleting the cookies in your browser for localhost:3000 and that should reset so the view can function once again before breaking.

Good luck