Base activated the Cobalt hard fork on mainnet on September 30 at 18:00 UTC after a week-long Sepolia test run. The upgrade bundles multiple infrastructure changes: refinements to the B20 native token standard, the introduction of validity and conditional transactions, and a framework for dynamic on-chain upgrade scheduling. Validity transactions allow submissions that only become eligible for inclusion when specified on-chain conditions are met; Base evaluates those conditions as blocks are built and can keep submissions private until inclusion.
Cobalt also moves Trusted Execution Environment (TEE) signer verification fully on-chain, speeding registration. Node operators had to upgrade to Base v1.4.2 or newer; major exchanges took precautions — Binance temporarily halted Base transfers during the window. Cobalt is the third major 2026 hard fork after Azul and Beryl, with Denim targeted for October. The changes are largely backward-compatible for deployed applications. The release aligns with Base’s push into tokenized finance: B20 was activated for stablecoins and real-world assets on July 8, and on August 25 Coinbase issued B20 tokens representing US-listed stocks (Apple, Nvidia, Meta, Alphabet). Base also plans to reduce block times from two seconds to 200 milliseconds and add protocol support for sponsored fees and bundled transactions, adopting some ideas from Ethereum’s Glamsterdam upgrade.