class ActiveRecord::RecordNotDestroyed

Raised by ActiveRecord::Base#destroy! when a record cannot be destroyed due to any of the before_destroy callbacks throwing :abort. See ActiveRecord::Callbacks for further details.

class User < ActiveRecord::Base
  before_destroy do
    throw :abort if still_active?
  end
end

User.first.destroy! # => raises an ActiveRecord::RecordNotDestroyed