Payment Gateway Migration in Practice: Assessment, Gradual Rollout, Rollback, and Finance Handover
The hard part of a payment gateway migration is not the API. It is the history of the money. Tokens usually cannot be moved, subscription mandates need to be re-established, historical orders still sit on the old gateway and can be refunded at any time, and reconciliation has to run across both gateways at once. This article covers triggers, six assessments, the three hardest things to move, parallel-run design, rollout order, rollback, finance handover, and a verification checklist.