migrating-motoko-actors

Motoko Actor Migrations Expert guidance for migrating actor state across canister upgrades with orthogonal persistence. Critical: Never use classical persistence or pre/post upgrade Do not use classical (legacy) persistence or system func preupgrade / system func postupgrade . They are error-prone, can leave canisters stuck if they trap, and do not scale. Also do not use the legacy (with migration = ...) actor-attached syntax. This skill covers mops-managed migrations . When a change requires an explicit migration, write it as a timestamped file in src/backend/migrations/ ; the chain replays automatically. How stable state is initialized Stable actor fields have no initializers in the actor body. The chain in src/backend/migrations/ is what gives them values: the runtime walks it in lexicographic order, running every file on a fresh install and only the files not yet applied to the canister on an upgrade. When to Use This Skill Show more Installs 1.4K Repository caffeinelabs/skills GitHub Stars 2 First Seen Aug 4, 2026 Security Audits Gen Agent Trust Hub Pass Socket Pass Snyk Pass