Ethereum Sets October 6 for Glamsterdam’s Sepolia Debut

Ethereum developers have scheduled Glamsterdam, the network’s next major upgrade, to activate on the Sepolia testnet on Oct. 6, bringing several protocol changes closer to live testing while leaving the mainnet timeline undecided.

The Ethereum Foundation said Sepolia node operators will need to upgrade both their execution-layer and consensus-layer clients ahead of the activation.

The testnet deployment will give developers an opportunity to evaluate Glamsterdam’s changes before any decision is made on its rollout to other networks.

Glamsterdam Brings Proposer-Builder Separation On-Chain

One of the upgrade’s key changes is enshrined proposer-builder separation (ePBS), which would bring the coordination between specialized block builders and validators directly into Ethereum’s protocol.

Today, that process relies on infrastructure outside the core protocol. By incorporating the mechanism at the protocol level, Glamsterdam is designed to reduce Ethereum’s dependence on external middleware for block production.

The upgrade will also introduce block-level access lists, which record the accounts and storage locations accessed within each block.

The feature is intended to give Ethereum more visibility into block-level state access while supporting changes to how transactions and blocks are processed.

Ethereum to Rework Gas Pricing

Ethereum Glamsterdam upgrade will also revise Ethereum’s gas pricing model to more closely reflect the costs associated with creating and accessing data on the network.

The changes could require developers to review contracts that depend on fixed gas stipends or hardcoded gas limits, according to the Ethereum Foundation.

That makes the Sepolia activation particularly important for developers, who will have an opportunity to identify compatibility issues before the upgrade progresses further through Ethereum’s testing process.

Mainnet Date Remains Open

Ethereum developers have not yet announced dates for Glamsterdam’s activation on Hoodi, the validator-focused testnet, or on the Ethereum mainnet.

The network is instead targeting 2027 for Hegotá, the upgrade expected to follow Glamsterdam.

Ethereum co-founder Vitalik Buterin said Hegotá could represent the network’s final “normal” fork before Ethereum’s development focus shifts toward areas including recursive STARKs, automated formal verification, optimized consensus and quantum-safe cryptography.

For now, Glamsterdam remains the immediate milestone. Its Sepolia activation will put some of Ethereum’s most significant proposed protocol changes through another round of real-world testing before developers determine when, and whether, the upgrade is ready for mainnet.