Ethereum has scheduled the Glamsterdam network upgrade for Sepolia on October 6, moving one of its largest Layer 1 redesigns from dedicated testing infrastructure onto a long-lived public testnet. According to the Ethereum Foundation’s official announcement, activation is set for epoch 353,024, slot 11,296,768, at 13:53:36 UTC. The Sepolia fork is a testnet activation, not a Mainnet launch, and Ethereum has not yet set dates for Hoodi or Mainnet.
The transition follows testing on Platåberget, the short-term public network Ethereum created specifically to expose Glamsterdam changes to validators, application developers and infrastructure operators before reaching Sepolia. That public Glamsterdam testing environment activated its fork in August after earlier private devnets. Sepolia therefore represents the next stage of the rollout rather than Glamsterdam’s first public deployment.
ePBS and Access Lists Reshape Block Processing
Glamsterdam combines the Amsterdam execution-layer upgrade with Gloas on the consensus layer. Its headline change, EIP-7732, introduces enshrined proposer-builder separation, or ePBS, directly into Ethereum’s consensus protocol. Builders commit to execution payloads before revealing them, while protocol rules handle payments to proposers and a payload-timeliness committee checks whether payloads and associated blob data arrive on time. The design moves part of proposer-builder coordination into Ethereum itself, reducing reliance on trusted middleware for that exchange.
EIP-7928 introduces block-level access lists, recording accounts and storage locations accessed within a block alongside relevant state changes. Clients can use that information to fetch state and validate transactions more concurrently. BALs are infrastructure for parallelized block processing rather than a claim that all Ethereum transactions will suddenly execute in parallel after October 6. The proposal builds on Ethereum’s broader roadmap toward higher gas capacity and parallel execution.
Gas accounting also changes materially. EIP-8037 separately meters state creation, while EIP-8038 reprices access to existing state, alongside changes covering intrinsic gas, calldata and block accounting. Contracts, wallets and infrastructure that hard-code gas assumptions may require changes even if their application logic itself remains intact. The Ethereum Foundation has specifically warned developers to test affected contracts and update gas estimation before production deployment.
Sepolia Operators Must Upgrade Both Clients
Sepolia node operators must update both execution and consensus clients before the fork. The Foundation has already confirmed compatible execution releases including go-ethereum 1.17.6, Nethermind 2.0.0, Besu 26.9.0, Erigon 3.7.0, Reth 2.7.0 and Ethrex 28.0.0, while confirmed consensus releases include Prysm 7.2.0, Teku 26.9.1 and Lodestar 1.49.0. Running software that understands the new rules is mandatory for nodes that intend to follow Sepolia after activation.
The validator transition is particularly significant because ePBS changes duties and builder interfaces. Earlier Prysm releases had already been preparing for Gloas and ePBS, but Sepolia now provides a persistent environment for observing those changes under a broader validator set. A compatible client release is a prerequisite for the fork, not evidence that Glamsterdam has activated on Ethereum Mainnet.
Glamsterdam also includes larger contract and initcode limits, ETH transfer logs, a slot-number opcode, new EVM stack instructions and consensus changes affecting slashed validators and validator churn. The upgrade is therefore broader than ePBS and BALs, although those two proposals remain its principal architectural changes for scaling block production and validation.
The next concrete milestone is Sepolia activation on October 6 at 13:53:36 UTC. Ethereum developers will then assess client interoperability, validator behavior, block production, gas repricing and application compatibility before deciding the Hoodi schedule. Only after the long-lived testnets prove stable will a separate Mainnet activation be announced. Until that happens, Glamsterdam remains a staged testnet upgrade rather than a production Ethereum fork.
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