As you may already know, Merb turned 1.0 a while ago and I decided to resume my studies to learn the framework. So I just built a new app with a few resources and fired the migration scripts: $ rake db:automigrate And this is what I got: Loading init file from /Users/leo/projects/merb/my-first-app/config/init.rb Loading /Users/leo/projects/merb/my-first-app/config/environments/development.rb ~ Connecting to database... /opt/local/lib/ruby/gems/1.8/gems/dm-core-0.9.6/lib/dm-core/adapters/data_objects_adapter.rb:137:in `initialize': wrong number of arguments (8 for 1) (ArgumentError)