I have a somewhat confusing error !! U I am using ruby 1.8.7 rails 2.0 and text mate and have observers that are defined in cofiguration file as config.active_record.observers = :flock_observer, :text_observer I cannot use migrate when this configuration is active, I had to delete it to be able to migrate. After the migration I add the configuration again and all is OK! What could be the reason for that behavior ? How could one fix it ?