It looks like a typo was introduced in the BandsController between B6 and B8. I looked in the first and last chapter version, but didn’t check every intermediate version. The code is not excerpted in the book, so the code download itself just needs to be updated.

  # lines 94-96
  # :genre_tags has an extra e :genere_tags
  private def band_params
    params.require(:band).permit(:name, :description, :genere_tags)
  end

I checked the create_bands migration and :genre_tags is spelled correctly there so you would not be able to update the attribute via the controller.