Base, the Coinbase-backed Ethereum Layer 2 network, activated its Cobalt hard fork on mainnet on September 30 at 18:00 UTC. The upgrade completed without significant disruptions after testing on the Sepolia test network and introduces infrastructure-level changes designed to enhance chain flexibility and streamline future upgrades.
Key Technical Changes
Cobalt delivers several engineering improvements across Base's operational stack. The upgrade refines the B20 native token standard, a precompile introduced during the earlier Beryl upgrade, improving reliability and consistency for tokens built on the standard.
The upgrade introduces validity and conditional transactions, which execute only if specific on-chain conditions are verified at the time of inclusion. If conditions are not met, the transaction does not execute.
A new framework for dynamic on-chain upgrade scheduling allows future hard forks to be scheduled and executed with reduced operational friction. Previously, coordinating hard forks required manual intervention and, in some cases, full restarts of client systems.
Cobalt also accelerates the registration process for Trusted Execution Environment (TEE) signers by moving verification fully on-chain, removing dependencies on off-chain verification steps.
Deployment and Exchange Response
All node operators were required to update their software to Base v1.4.2 or newer ahead of activation. Major exchanges took precautionary measures during the upgrade window. Binance halted transfers on Base during the activation, with reports indicating the rollout proceeded cleanly.
Upgrade Cadence and Backward Compatibility
Base has pursued an aggressive upgrade schedule in 2026, with Azul activating on June 25, Beryl following afterward, and Cobalt landing at the end of September. The next hard fork, Denim, is targeted for October 2026.
For existing developers and protocols on Base, Cobalt changes are largely backward-compatible. While the node software update was mandatory, application-level code does not require significant modifications. New transaction types are additive, meaning existing transaction formats continue to function as before.
