Optimism Upgrade 20 Nears Completion with Testnet Switch
Optimism's Upgrade 20 has been approved by governance voting, paving the way for four OP Stack testnets to move from Output Root Dispute Games to Super Root Dispute Games on September 17. If a seven-day soak period goes smoothly, mainnet will follow suit on September 24.
The switch to Super Root is seen as a prerequisite for cross-chain interoperability, as it allows multiple chains to be represented at the same timestamp. However, each chain's dispute infrastructure will still remain separate, and the change only affects the way disputes are anchored.
For users, nothing changes - previously submitted withdrawal proofs remain valid, and OptimismPortal continues to accept both dispute-game formats. Chain operators and developers need to update their systems to support Super Root, including fault-proof infrastructure providers and app developers using viem/op-stack for withdrawal proving.