Isthmus

Overview of the Isthmus hardfork, incorporating Ethereum Pectra EIPs and introducing the operator fee mechanism for sequencer revenue.

Activation Timestamps

Network	Activation timestamp
mainnet	1746806401 (2025-05-09 16:00:01 UTC)
sepolia	1744905600 (2025-04-17 16:00:00 UTC)

Execution Layer

• Pectra (Execution Layer):
  • EIP-7702
    • Span Batch Updates
  • EIP-2537
  • EIP-2935
    • EIP-2935 Contract Deployment
  • EIP-7002
    • The EIP-7002 predeploy contract and syscall are not adopted as part of Base.
  • EIP-7251
    • The EIP-7251 predeploy contract and syscall are not adopted as part of Base.
  • EIP-7623
  • EIP-6110
  • EIP-7685
• L2ToL1MessagePasser Storage Root in Header
• Operator Fee

Consensus Layer

• Isthmus Derivation

Smart Contracts

• Predeploys
• L1 Block Attributes
• System Config