Rails: Is there an update or update_attributes that throws exception on failure?

Just an update.. on update! :)

update! exists since Rails 4 and update_attributes!, which was available since Rails 3, has since become just an alias for update!.

I'm not sure why you think there is no update_attributes! because there is. If you were reading the apidock you might have come across an issue such as they talked about here: Why is ActiveRecord::Base#update_attributes deprecated?

Here are the docs detailing the method you want: http://apidock.com/rails/v3.2.13/ActiveRecord/Persistence/update_attributes%21

But, yes, there is an update_attributes! that will raise an exception on validation failure. It calls save! under the hood.