This morning, the Ruby package for Arch Linux was upgraded from version 1.8.7 to 1.9.1. Unfortunately, after the upgrade all Rails applications (using Rails 2.3.4) stopped to work and showed an error like:
undefined method `^' for "b":String (NoMethodError)
Fortunately, I am not the first one who encountered this issue, and so it is already fixed in the Rails git repository. To fix it on my local installation, I simply had to replace /<path_to_ruby_gems>/activesupport-2.3.4/lib/active_support/message_verifier.rb with the corresponding file from the git repository. And with that, my applications started to work again :)
thx, man ))