Base Schedules Cobalt Upgrade With Conditional Transactions and Fork Automation
The Sept. 30 hard fork includes B20 token changes, on-chain upgrade scheduling and Trusted Execution Environment signer verification.
Base, an Ethereum Layer 2 network, has scheduled its Cobalt hard fork for Sept. 30 to add condition-based transactions, upgrade automation and changes to token and signer infrastructure.
The upgrade is set for 2 p.m. ET (18:00 UTC), with a maintenance window scheduled through 4 p.m. ET (20:00 UTC). Node operators must run Base software version 1.4.2 or later. That release added Cobalt support for Base Mainnet and Base’s consensus client.
Cobalt introduces validity transactions, which allow signed transactions to become eligible only after specified balance, storage, block-number or Flashblock-index conditions are met. The feature supports legacy, EIP-2930 and EIP-1559 transactions, although Mainnet availability has not yet been confirmed.
The upgrade also expands the B20 token standard with scheduled multiplier updates, simpler transfer-blocking functionality and new Union and Intersect policies.
Cobalt adds an automated process for future network upgrades. An Ethereum smart contract will store fork timestamps, allowing Base nodes to read the schedule and activate upgrades at the designated time without a client restart. The dynamic-upgrade system is being rolled out in metrics-only mode on Mainnet.
The hard fork also changes registration for Trusted Execution Environment (TEE) signers. AWS Nitro attestations will be verified fully on-chain using checked P-384 hints, replacing the previous RISC Zero and Boundless proving flow.
Base Sepolia completed its Cobalt upgrade at 4 p.m. ET (20:00 UTC) on Sept. 23 after starting at 2 p.m. ET (18:00 UTC). No incidents were reported on Sept. 30, but Mainnet activation had not been explicitly confirmed as completed.
