A migration plan is a documented process for moving data, users, settings, or services from one system to another before the old system is retired. It usually defines what will be moved, when it will happen, how access will be verified, and what backups or rollback steps exist if something fails.
In cyber security, migration plans matter because shutdowns, upgrades, and vendor changes can create availability and data-loss risks. A bad migration can leave users locked out, break authentication, or expose data during transfer. Defenders use migration plans to preserve access, maintain audit trails, and reduce downtime through export tools, staged cutovers, and clear deadlines. Attackers may also exploit weak migrations by targeting transfer windows, stolen credentials, or insecure legacy endpoints that stay online too long.