Cairo Upgrades

Contents

• Starknet Upgrade Model
• Using the OpenZeppelin Upgradeable Component
• Access Control
• Upgrade Safety

Starknet Upgrade Model

Starknet separates contract instances from contract classes. A class is the compiled program (identified by its class hash); a contract is a deployed instance pointing to a class. Multiple contracts can share the same class.

Upgrading a contract means replacing its class hash so it points to a new class. The contract keeps its address, storage, and nonce — only the code changes. This is fundamentally different from EVM proxy patterns: