We are announcing the upcoming Upgrade 16 for Metal L2. This release includes critical changes to the OP Stack’s L1 contracts and op-challenger component, forming part of long-term protocol evolution plans. The changes introduce groundwork for future interoperability and adjustments for updated Stage 1 criteria.

The Upgrade 16 hard fork will be activated on Wed July 24 2025 16:00:00 UTC (1753372800) for the Mainnet Superchain. This applies to all chains that have opted into the hard fork inheritance behavior. Note: This is a timestamp, not a block height.

IMPORTANT: Do not rely on pending L1 withdrawals completing before the upgrade. Any unfinalized withdrawals must be reproven after Upgrade 16 is active.

Included in Upgrade 16:

• Interop-Ready Smart Contracts
  Updates to the OptimismPortal contract prepare the OP Stack for future cross-chain messaging. These changes do not activate interoperability but lay the foundation for later stages.

• MAX_GAS_LIMIT Adjustment
  The MAX_GAS_LIMIT is increased from 200 million to 500 million gas, following infrastructure improvements and greater assurance in the Cannon proof system.

• Stage 1 Compliance Updates
  To align with L2Beat's January 2025 Stage 1 requirements, the following contract changes are made:

  • The DeputyGuardianModule is removed.

  • The DeputyPauseModule is updated.

Chain operators must upgrade their infrastructure ahead of the hard fork to avoid service disruption. For full instructions, timing details, and reproving guidance, refer to the Upgrade 16 Notice Page and the Release Management Project Board. For coordination and support, use the Optimism Discord.