Optimism introduces major updates to fault proofs, affecting the withdrawal process for bridges and exchanges on the OP Mainnet and OP Sepolia.
Optimism (OP), the leading layer 2 scaling solution for Ethereum, will be implementing significant changes to its fault proof system. This directly impacts bridges, centralized exchanges, and custom solutions that handle withdrawals. This development is very important for stakeholders within the Optimism ecosystem as it requires them to adapt their systems to the new withdrawal confirmation process.
Fault Prevention System Update Overview
The upgrade moves from L2OutputOracle to a new system consisting of OptimismPortal and DisputeGameFactory. L2OutputOracle, previously essential to the proposer role of storing L2 state output proposals, is completely removed. Instead, developers must use the dispute game’s rootClaim to prove their withdrawal in the first step of a two-step withdrawal process.
This causes a slight change, as the OptimismPortal contract now references the DisputeGameFactory contract instead of L2OutputOracle. Developers must now retrieve recent DisputeGame contracts with the appropriate game type via OptimismPortal to prove their withdrawal. These changes increase the security and decentralization of the withdrawal process, but require developers to update their client code accordingly.
Impact on bridges and centralized exchanges
Switching to fault proof requires updating your fetch processing logic. Most teams leveraging the Optimism SDK or Viem will need to update their software versions prior to the Sepalia release. For example, the Optimism SDK must be upgraded to version 3.2.0 or higher to maintain API compatibility and automatically incorporate new logic when defect proof upgrades are detected.
If you use Viem, you will need to use an experimental decorator that supports error proofing, as the API is broken in newer versions. Once fault tolerance becomes mainstream on the mainnet, a transition to a stable API is recommended.
Monitor system changes
The Withdrawal Monitor and Dispute Monitor services have been updated to accommodate the new fault prevention system. The Withdrawal Monitor service, which is critical to the two-step withdrawal system, is slightly slower at launch but is now more stable and compatible with a wider range of infrastructure. Fully backwards compatible with existing systems.
The Dispute Monitor service, on the other hand, replaces the current Error Monitor to detect invalid output proposals. Teams currently running Fault Monitor will need to switch to the new service and update their alerting systems to comply with the new upgrade.
Next steps for developers and operators
Developers and operators within the Optimism network are encouraged to review the detailed documentation provided by Optimism to familiarize themselves with any upcoming changes. This includes understanding the three main components of the fault-tolerant system (Cannon FPVM and Mips.sol) and preparing those systems for the transition.
The proof-of-fault update is scheduled to be released on testnet on March 19, 2024. To ensure smooth integration with new protocols and avoid operational disruption, it is important for all parties involved to prepare their systems in advance.
Optimism continues to provide developer support for those experiencing difficulties during the transition. Active engagement and detailed documentation reflect Optimism’s commitment to maintaining a strong, developer-friendly ecosystem.
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