Let event be the result of using .

Set event’s [type](https://dom.spec.whatwg.org/#dom-event-type) attribute to ““.

Set event’s [bubbles](https://dom.spec.whatwg.org/#dom-event-bubbles) and attributes to false.

Let legacyOutputDidListenersThrowFlag be initially false.

If transaction’s state is , then set transaction’s state to .

Dispatch event at request with legacyOutputDidListenersThrowFlag.