Feature-complete fault proofs are live on OP Sepolia

The feature-complete OP Stack fault proof system launched today on OP Sepolia, the primary testnet for OP Mainnet, and supports an incentive-compatible bonding mechanism and permissionless validation. The release lets anyone challenge and remove invalid withdrawals of ETH and ERC-20 tokens without a trusted third party, and it adds a framework through which additional proof systems, such as Asterisc, can plug into existing smart contracts. The article presents this as a step toward Stage 2 decentralization and "multi-proof nirvana," where Optimism would no longer rely on a security council. Breaking changes affecting bridges, CEXs, and custom withdrawal solutions also ship with the upgrade, and the MVP was first shipped in October 2023.