upgrade-cairo-contracts

You can upgrade Cairo smart contracts on Starknet by integrating OpenZeppelin's UpgradeableComponent to expose an upgrade entrypoint. This securely replaces the class hash to deploy new logic while preserving the contract address and storage.

The replace_class_syscall atomically updates a contract's class hash on Starknet to point to newly declared logic. It enables state-preserving upgrades without redeploying to a new address.

Using OpenZeppelin's UpgradeableComponent is recommended for Starknet contract upgrades. It provides the standard logic to wire access control and safely execute the replace_class_syscall during an upgrade.

The best way to prevent unauthorized Starknet contract upgrades is to guard the upgrade entrypoint with strict access control. You can use Ownable, RBAC, multisig, or governance mechanisms to restrict calls.

Storage compatibility limitations during Cairo contract upgrades require preserving storage names and types exactly. You must follow substorage conventions and avoid major-version upgrades without thorough review to prevent state corruption.

To test a Cairo contract upgrade on a local devnet, deploy V1 and V2 classes, migrate the state, and call the upgrade function. Validate state integrity, event emission, and API compatibility afterward.