Ethereum’s Glamsterdam upgrade activates on Sepolia

Ethereum’s next protocol fork combines consensus- and execution-layer changes; Glamsterdam activated on the Sepolia testnet on Oct. 6, according to the Ethereum Foundation’s testnet announcement. The activation took place at epoch 353,024, slot 11,296,768, at 13:53:36 UTC.

The Sepolia fork gives client teams and developers a public network to evaluate changes to block production, state access and gas accounting before any mainnet date is set.

Glamsterdam combines Amsterdam, an execution-layer upgrade, with Gloas, a consensus-layer upgrade. The Foundation’s schedule lists Hoodi and mainnet activation dates as undecided, so the Sepolia launch does not itself set a timetable for Ethereum’s main network.

What protocol changes are being tested?

The fork introduces enshrined proposer-builder separation (ePBS) and block-level access lists (BALs), the Foundation says. Under EIP-7732, the protocol moves the separation between block proposers and builders into Ethereum’s consensus rules: a proposer includes a builder’s commitment to an execution payload, which the builder then reveals. The protocol handles payment, reducing reliance on trusted middleware for that exchange.

EIP-7928 adds enforced access lists that record which accounts and storage locations a block touches, together with post-transaction state changes. The Foundation says clients can use these lists to read state and validate transactions in parallel, then compute state roots more efficiently. Together, the two changes alter how blocks are produced and validated.

How does Glamsterdam change gas accounting?

The upgrade also adjusts gas costs to better reflect resource use and state growth. The Foundation says EIP-8037 increases and separately meters the cost of creating state, while EIP-8038 updates state-access costs; additional changes affect transaction gas, calldata, access lists and block accounting.

Alchemy’s report on the Sepolia activation says the testnet is running with a 200 million gas limit and marks the first public-network test of EIP-8037. The firm says contract deployments and other operations that write new storage cost more under the repricing, and that gas estimates based on earlier assumptions may undercount those costs.

What comes next for operators and developers?

Before Sepolia’s activation, node operators needed to update both execution- and consensus-layer clients, the Foundation said. Validators also needed to update their beacon node and validator client. The Foundation’s release table lists compatible versions across clients including Geth, Besu, Nethermind, Lighthouse, Prysm and Teku.

For application teams, the Foundation advises testing contracts and gas estimates against Sepolia and checking dependencies on fixed gas assumptions, logs, opcodes and client interfaces. The testnet launch gives those teams a place to assess the changes; the Foundation says Hoodi and mainnet schedules will be announced separately once client teams decide them.

Sources

• Ethereum Foundation’s testnet announcement — blog.ethereum.org
• report on the Sepolia activation — alchemy.com