Optimism (OP) Announces Critical Fault Proof Upgrade Impacting Bridges and Exchanges

Optimism is rolling out major updates to Fault Proofs affecting withdrawal processes for OP Mainnet and OP Sepolia bridges and exchanges.

Optimism (OP), a leading Tier 2 scaling solution for Ethereum, is set to implement significant changes to its error proofing system that will directly affect bridges, centralized exchanges, and custom solutions that handle withdrawals. This development is critical for stakeholders within the Optimism ecosystem as they must adapt their systems to align with the new withdrawal verification process.

Review of the update to the error proofing system

The upgrade introduces a move from L2OutputOracle to a new system including OptimismPortal and DisputeGameFactory. The L2OutputOracle, which was previously essential to the Proposer’s role in storing output proposals for L2 state, will be deprecated entirely. In its place, developers will have to use a disputed game’s rootClaim to prove withdrawals during the first step of the two-step withdrawal process.

The OptimismPortal contract will undergo minor changes as it now references the DisputeGameFactory contract instead of L2OutputOracle. Developers must now search for recent DisputeGame contracts with the appropriate game type through OptimismPortal to prove withdrawals. This change improves the security and decentralization of the withdrawal process, but requires developers to update their client code accordingly.

Impact on bridges and centralized exchanges

The move to Fault Proofs requires updates to the withdrawal processing logic. Most teams using the Optimism SDK or Viem will need to update their software versions prior to the release of Sepolia. The Optimism SDK, for example, requires an upgrade to version 3.2.0 or higher, which supports API compatibility and integrates the new logic automatically after a bug-proof upgrade is detected.

For those using Viem, the latest version breaks the API, forcing the use of an experimental decorator that supports bug proofs. After incorporating the bug evidence into the mainnet, a switch to the stable API will be recommended.

Changes to the monitoring system

The withdrawal monitoring and dispute monitoring services have undergone updates to accommodate the new bug protection system. The pull monitor service, which is critical to the two-step pull system, has become slightly slower to launch, but more reliable and compatible with a wider range of infrastructure. It remains fully backwards compatible with existing systems.

The Dispute Monitor service, on the other hand, will replace the current Fault Monitor for detecting invalid output proposals. Teams currently running Fault Monitor will need to migrate to the new service and update their alerting systems to stay compliant with the new upgrade.

Next steps for developers and operators

Developers and operators within the Optimism network are advised to familiarize themselves with the upcoming changes by reviewing the detailed documentation provided by Optimism. This includes understanding the three main components of the Fault Proof System—Cannon FPVM and Mips.sol—and preparing their systems for the transition.

The Fault Proof updates are scheduled to launch on the testnet on March 19, 2024. It is critical that all parties involved prepare their systems in advance to ensure seamless integration with the new protocol and avoid any disruptions to their operations.

Optimism continues to provide developer support for those experiencing difficulties during the transition. Proactive engagement and detailed documentation reflect Optimism’s commitment to maintaining a stable and developer-friendly ecosystem.

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