Ethereum Glamsterdam mainnet upgrade

Ethereum's Glamsterdam network upgrade is tentatively planned for mainnet in December 2026, though no date has been agreed. The upgrade affects ETH and the Ethereum base layer and follows the Fusaka upgrade.

What is happening

Glamsterdam is the next Ethereum hard fork after Fusaka. Its main changes are enshrined proposer-builder separation (ePBS, EIP-7732), block-level access lists (EIP-7928) and a repricing of gas for creating and accessing state. The scope is tracked in EIP-7773, which schedules 18 core changes.

The upgrade went live on the Sepolia testnet on Oct. 6, 2026, and reportedly went smoothly. Developers have scheduled the Hoodi testnet, the second and final public testnet, for Oct. 26, with client releases expected by Oct. 16.

Mainnet timing remains open. The Ethereum Foundation said the Hoodi and mainnet dates had not yet been decided, and ethereum.org lists only a fourth-quarter 2026 target. A draft scheduling proposal on GitHub floats Dec. 1, 8 and 9 as possible mainnet slots, but developers have not agreed on any of them. Several proposals, including EIP-2780 and EIP-8037, remain in Last Call review until Nov. 1, so the scope may still change.

Why it matters

Glamsterdam shifts Ethereum's focus toward scaling the base layer. ePBS moves the handoff between proposers and builders into the protocol, reducing reliance on trusted relays. Block-level access lists let clients process transactions in parallel, and the new gas schedule is a prerequisite for raising the gas limit. Ethereum.org lists a 200 million gas floor as the post-upgrade target, more than triple today's 60 million default.

The effect on fees depends on demand and validator adoption. Costs of creating state rise sharply, while plain transfers and some other operations may become cheaper. Stakers are expected to see faster exits, but the weak subjectivity period shortens from about 15.7 to about 7 days. Open questions include builder concentration and Sybil risks, and early Sepolia data suggested a thin builder market, which makes the Hoodi test more telling.

Key details

• Date: December 2026 (tentative; draft options are Dec. 1, 8 and 9; no mainnet date agreed)
• Project: Ethereum
• Coins: ETH
• Category: Network Upgrade
• Status: Tentative
• Source: https://yellow.com/research/glamsterdam-ethereum-18-change-bet-base-layer