Inline Actor Migration Migrate actor state across canister upgrades using a migration expression attached to the actor. Each upgrade has at most one migration function. For multi-migration with a directory , load instead. When to Use Implicit migration (no code needed) The runtime allows the upgrade if the new program is compatible with the old: - Adding actor fields - Removing actor fields - Changing mutability ( ↔ ) - Adding variant constructors - Widening types ( → ) Explicit migration required - Renaming fields - Changing a field's type (e.g. → variant, → ) - Restructuring state (splittin…