Key Takeaways
BlockchainReporter covers Base activating its Cobalt hard fork on mainnet, introducing conditional validity transactions and B20 token updates.
According to BlockchainReporter, Base is set to activate its Cobalt hard fork on the mainnet on September 30. The network upgrade, which went live on the Base Sepolia testnet on September 23, introduces conditional validity transactions, improves the B20 token standard, lays the groundwork for onchain-scheduled node upgrades, and modifies the trusted-execution-environment prover registration flow.
BlockchainReporter notes that Cobalt is the network's third upgrade of 2026, following the Azul and Beryl forks, with the Denim upgrade targeting October. Cobalt expands the B20 standard with scheduled multiplier updates, new Union and Intersect policy types, and a simplified transfer-blocking mechanism. Additionally, validity transactions allow Base to include signed transactions only when specified onchain conditions match.
The upgrade also implements dynamic upgrades via an Ethereum smart contract and updates TEE prover registration by verifying AWS Nitro attestations fully onchain using P-384 hints. Built on the OP Stack, Base continues its 2026 upgrade schedule following previous enhancements to security, decentralization, and token issuance.
Source & Fact-Check Note
https://blockchainreporter.net/base-cobalt-hard-fork-mainnet/
