here is the migration after " create_table :users, id: :ulid do |t| t.string :name t.timestamps end "

add this forget about it #config/initializers/ulid_primary_key_defaults.rb module ActiveRecord module ConnectionAdapters class TableDefinition alias_method :original_primary_key, :primary_key def primary_key(name, type = :bigint, options) if type == :ulid && !options.key?(:default) options[:default] = -> { "gen_ulid()" } end original_primary_key(name, type, options) end end end end