Optimism approves Upgrade 20 for Super Root dispute games

CryptoSlate reports that Optimism governance approved Upgrade 20 following a vote held on Sept. 16. The update transitions the fault-proof mechanism from Output Root to Super Root Dispute Games, changing the method OP Stack chains use to verify state accuracy prior to the finalization of withdrawals to Ethereum.

The rollout involves four specific testnets: OP Sepolia, Ink Sepolia, Soneium Minato, and Unichain Sepolia. A contract update is scheduled for these networks on Sept. 17. Mainnet deployment is targeted for Sept. 24, contingent upon the new infrastructure finishing a seven-day testnet period.

Within this framework, permissioned chains will adopt game type 5, whereas permissionless fault-proof setups will utilize game type 9. Super Root games rely on timestamps to anchor state assertions, establishing the synchronized time reference needed for Superchain interoperability.

Additional modifications to the contracts manager and SystemConfig introduce safeguards for upgrade sequencing and remove legacy configuration functions. Developers utilizing viem/op-stack for withdrawal proofs must upgrade to version 2.51.0 or higher and incorporate the L2 timestamp into the proving process. Withdrawal proofs submitted under the previous standard remain valid, and OptimismPortal will continue to support both dispute-game formats.