add_category_to_food_items.rb

class AddCategoryToFoodItems < ActiveRecord::Migration
  def change
    add_column :food_items, :string, :category
  end
end

error

$ bundle exec rake db:rollback STEP=1
==  AddCategoryToFoodItems: reverting =========================================
-- remove_column("food_items", :string)
rake aborted!
An error has occurred, this and all later migrations canceled:

undefined method `to_sym' for nil:NilClass

Tasks: TOP => db:rollback
(See full trace by running task with --trace)