It seems that ActiveRecord cannot return sane errors when some constraint on a database operation is not met, for instance if you forget to set an attribute which has a “NOT NULL” constraint. If this happens AR simply throws an InvalidStatement exception. You would have to actually search your database logs for the error message. This really sucks! Also check out this blog post on the same topic. Oh well, perhaps I should try and fix this issue instead of griping, it’s open source after all. You can of course also argue that the model file in the Rails app was not complete (:allow_nil => false)..