Ethereum schedules Glamsterdam testnet upgrade for Oct. 6

Ethereum developers will activate the Glamsterdam upgrade on the Sepolia testnet on Oct. 6. The Ethereum Foundation advised that node operators update both execution-layer and consensus-layer clients before activation to avoid service disruptions.

Glamsterdam enshrines proposer-builder separation, moving the handoff between specialized block builders and validators into the protocol. The change formalizes how block builders and validators interact.

The upgrade adds block-level access lists that record which accounts and storage slots are used in each block. The upgrade revises gas pricing to better align fees with the cost of creating and accessing data on the network.

The Foundation warned the gas repricing may affect smart contracts that assume fixed gas stipends or use hardcoded gas limits, and those contracts could require code changes. Developers and teams running test deployments are being asked to review contract dependencies and client configurations ahead of Oct. 6.

The activation applies only to Sepolia. Developers have not set dates for Glamsterdam on the validator-focused Hoodi testnet or for mainnet. The community will test and iterate on Sepolia before scheduling broader rollouts.

Developers expect the next major upgrade, Hegotá, in 2027. Ethereum co-founder Vitalik Buterin wrote that Hegotá could be the network’s last ‘normal’ fork before development shifts to technologies such as recursive STARKs, automated formal verification, optimized consensus designs and quantum-resistant cryptography.

Node operators who do not update both execution and consensus clients risk becoming unsynced or unable to validate new blocks after the Sepolia activation, the Foundation warned.