How to Fix Symfony Messenger's Dual-Write Problem Using a Transactional Outbox

The dual-write problem occurs when an application writes to a database and a message broker separately, with no shared transaction guaranteeing both succeed or fail together. In Symfony Messenger, using DispatchAfterCurrentBusStamp with the doctrine_transaction middleware prevents ghost events but still leaves a gap where a committed order may never notify downstream systems if the broker is unavailable. The true fix is a transactional outbox pattern, where the event record is inserted into the database within the same transaction as the business data. Symfony Messenger's Doctrine transport acts as a database table, meaning routing messages to it causes a plain SQL INSERT that can participate in an open transaction. By wiring the dispatch to a Doctrine transport without deferring it past the commit, both the order and the outbox event are saved atomically, closing the reliability gap entirely.