Make availability a requirement
Translate the business requirement into an agreed interruption window, recovery objective, and validation criteria. Some architectures support uninterrupted transitions; others require a short controlled pause. Establish those constraints before promising a downtime target.
Move dependencies into view
Map application services, databases, background jobs, integrations, identity, and DNS. A workload can appear healthy while a dependent service still points at the old environment. Test the full business transaction, not only the home page.
Rehearse the final switch
Validate replicated data, define how writes will be handled, and document the traffic change. Agree who can stop the migration and what triggers rollback. Microsoft’s migration guidance emphasizes testing, replication, and controlled final cutover for minimal-downtime approaches.
Keep observing after the switch
Watch error rates, business transactions, queues, and data consistency after the new environment receives traffic. Keep the old environment available for the agreed rollback period and retire it only after validation.