Isthmus

Hardfork registry entry for the Isthmus network upgrade, which brought L1’s Pectra upgrade to the OP Stack and added the operator fee.

Isthmus brought Ethereum’s Pectra upgrade to the OP Stack and introduced the operator fee.

Status	Active
Governing spec	specs.optimism.io
Governance approval	proposal
Operator notice	Upgrade 15 notice
Mainnet activation (superchain default)	Fri, 09 May 2025 16:00:01 UTC (1746806401)
Sepolia activation (superchain default)	Thu, 17 Apr 2025 16:00:00 UTC (1744905600)

Minimum component versions (from Upgrade 15 notice):

Component	Minimum version
op-node	v1.13.2
op-geth	v1.101503.4
op-batcher	v1.12.0
op-challenger	v1.4.0

What changed

Per the spec overview:

• Pectra EIPs on L2, including EIP-7702 (set EOA account code), EIP-2537 (BLS12-381 precompiles), EIP-2935 (historical block hashes in state), and EIP-7623 (increased calldata cost). The EIP-7002 and EIP-7251 predeploy contracts and syscalls are not adopted by the OP Stack.
• L2ToL1MessagePasser storage root in the block header.
• Operator fee.
• Smart contracts: predeploy, L1 block attributes, and SystemConfig updates.

The Upgrade 15 notice covers the operator steps that accompanied activation.