$ rails new ~/work/foo --edge -d mysql (snip) $ cd ~/work/foo # modify to `encoding: utf8mb4` $ vi config/database.yml $ rake db:create db:migrate rake aborted! ActiveRecord::StatementInvalid: Mysql2::Error: Specified key was too long; max key length is 767 bytes: CREATE UNIQUE INDEX `unique_active_record_internal_metadatas` ON `active_record_internal_metadatas` (`key`) /Users/kamipo/work/foo/vend