Protocol Upgrade Proposal Process

A Protocol Upgrade Proposal (PUP) is the formal mechanism for changing the OP Stack specification. Once approved, a PUP does not merely suggest a change—it creates a mandatory upgrade requirement for OP Mainnet and, under the Law of Chains, for all chains that have opted into Superchain governance. The process begins with a technical specification, moves through Token House approval, and is subject to a Citizens' House veto before the Security Council executes the onchain upgrade transaction. Chain operators and infrastructure teams must track this pipeline because the activation delay is finite and non-negotiable.

The mandatory nature of a PUP is enforced by the ProtocolVersions contract, which records the current recommended and required versions. After the Security Council initiates an upgrade, a time-locked activation delay begins. Once this delay expires, the new protocol version becomes required, and any node running an older version will stop syncing at the activation block. This means exchanges, RPC providers, indexers, and bridge operators must complete their op-geth and op-node upgrades before the deadline or face an effective network halt. The delay is designed to give operators time to prepare, but it also creates a hard coordination point across the entire Superchain.

For teams operating OP Stack chains, the impact extends beyond a single client update. A PUP can alter derivation rules, change precompile behavior, modify gas or fee parameters, or introduce new cross-chain messaging semantics. These changes can break dependent systems such as wallets, bridges, or monitoring tools that rely on specific execution-layer behavior. Chainscore Labs helps operators and builders navigate this process with upgrade readiness reviews that map the exact technical changes in a PUP to the systems they affect, ensuring that integration code, monitoring alerts, and operational runbooks are updated before the activation deadline.

A protocol upgrade for Optimism and the OP Stack begins as a technical specification, often a design document or pull request against the op-stack repository, that defines a change to the execution client, derivation pipeline, or fault proof system. This specification is the source of truth for what the upgrade changes at the protocol level. It must be precise enough for client implementers, chain operators, and security auditors to understand the new behavior, any breaking changes to state transition, and the required software versions. The specification phase is where the scope of a Superchain Upgrade Proposal (SUP) is set, and it directly determines the integration work required by every OP Stack chain that intends to remain part of the Superchain.

Once a specification is stable, it enters the Optimism Collective governance process as a Protocol Upgrade Proposal (PUP). The Token House votes on whether to approve the upgrade. If approved, the proposal moves to the Security Council, which has the authority to activate a built-in delay or to veto the upgrade if a critical issue is discovered. This is not a ceremonial step; the Security Council's multisig is the practical control point for the upgrade transaction on OP Mainnet. For other OP Stack chains, the governance path varies: chains operating under the Law of Chains are expected to execute the upgrade to maintain Superchain compatibility, while independent chains must decide whether to adopt the change. The activation is not simultaneous—OP Mainnet typically upgrades first, followed by a window for other chain operators to prepare and execute.

For node operators, exchanges, and infrastructure teams, the period between Token House approval and the activation deadline is the critical readiness window. Teams must upgrade op-geth and op-node to the required versions, validate that their monitoring and alerting logic aligns with any new protocol behavior, and coordinate with partners on testnet verification. A missed upgrade can result in a chain halt or a divergence from the canonical Superchain state. Chainscore Labs provides upgrade readiness reviews that map the specification to your operational stack, identify breaking changes in derivation or execution, and validate that your integration and monitoring systems are prepared for the activation. For chain operators evaluating whether to adopt a PUP, we offer impact assessments that model the operational and economic consequences of the change.