Ethereum is set to undergo its next major network transformation, dubbed "Glamsterdam," a significant upgrade designed to accelerate the network’s L1 scaling roadmap. Following the successful implementation of the Fusaka upgrade in November 2025, Glamsterdam represents a fusion of two distinct technical advancements: the Amsterdam execution layer upgrade and the Gloas consensus layer upgrade. By introducing enshrined Proposer-Builder Separation (ePBS) and block-level access lists, the Ethereum core development team aims to fundamentally improve how blocks are produced, validated, and scaled.
The upgrade is officially scheduled for activation on the Sepolia testnet at epoch 353,024 and slot 11,296,768, occurring on October 6, 2026, at 13:53:36 UTC. While this announcement provides a clear path forward for developers and node operators on Sepolia, the timeline for mainnet deployment and the Hoodi testnet remains under deliberation by the client teams.
Main Facts: What is Glamsterdam?
Glamsterdam is a comprehensive protocol overhaul that targets the primary bottlenecks in Ethereum’s current architecture: block production latency, state growth, and the efficiency of transaction validation. The upgrade is defined by three primary pillars of innovation:
1. Enshrined Proposer-Builder Separation (ePBS)
The centerpiece of the upgrade, detailed in EIP-7732, is the enshrinement of proposer-builder separation within the protocol itself. Currently, Ethereum relies on external, centralized middleware to manage the exchange between block proposers (validators) and block builders (specialized actors who construct optimal blocks).
By enshrining this process, the protocol will now handle the inclusion of a builder’s commitment to an execution payload directly. This reduces the network’s reliance on third-party trust, enhances censorship resistance, and provides a more robust framework for payload validation. Furthermore, it separates consensus validation from execution validation, granting validators more time to verify payloads without delaying the slot timing—a crucial improvement for maintaining L1 throughput.
2. Block-Level Access Lists (BALs)
EIP-7928 introduces mandatory block-level access lists. By requiring transactions to specify the accounts and storage slots they intend to access, the network can significantly optimize its performance. These lists allow Ethereum clients to read state from the disk in parallel and validate transactions simultaneously rather than sequentially. This is a game-changer for node performance, as it enables more efficient state root computation and reduces the overhead required for block processing.
3. Gas Repricing and State Growth Management
To ensure that gas costs remain aligned with the actual computational resources consumed, Glamsterdam introduces a series of repricing EIPs (EIP-8037 and EIP-8038). These updates increase the cost of state creation and adjust the pricing for state access. By better reflecting the cost of state growth, the Ethereum network aims to disincentivize inefficient data storage practices, ensuring the blockchain remains lightweight enough for node operators to maintain over the long term.
Chronology of Development
The path to Glamsterdam has been a multi-year effort of rigorous research and cross-client coordination. Since the conclusion of the Fusaka upgrade in late 2025, the Ethereum Improvement Proposal (EIP) process has focused heavily on refining the specifications for ePBS.
- Mid-2025: Initial research and testing of the ePBS framework and the Gloas consensus mechanisms began in private devnets.
- Late 2025 (November): The successful activation of the Fusaka upgrade paved the way for the architectural changes required for Glamsterdam.
- September 17, 2026: Formal announcement of the Glamsterdam testnet deployment schedule, providing the industry with the necessary notice for infrastructure updates.
- October 6, 2026: Scheduled activation on the Sepolia testnet.
- Post-October 2026: Monitoring and performance evaluation on Sepolia will determine the readiness of the mainnet deployment.
Supporting Data and Technical Specifications
The technical weight of the Glamsterdam upgrade is documented through several critical EIPs. Below is a breakdown of the primary changes:
| EIP Reference | Title | Function |
|---|---|---|
| EIP-7732 | Enshrined PBS | Formalizes the separation of proposers and builders at the protocol level. |
| EIP-7928 | Block-Level Access Lists | Enables parallel state access and validation for increased throughput. |
| EIP-8037 | State Creation Pricing | Increases gas costs for state-heavy operations to curb state bloat. |
| EIP-8038 | State Access Pricing | Adjusts the cost of reading data to reflect current hardware limitations. |
In addition to these major changes, the upgrade includes several quality-of-life improvements for developers, such as:
- New Stack-Manipulation Instructions: Providing more flexibility for smart contract compilation.
- Increased Contract Size: Allowing for larger, more complex decentralized applications (dApps).
- Deterministic Factory Contracts: Simplifying deployment patterns for cross-chain applications.
- Slot-number Opcode: Allowing smart contracts to become more aware of their position in the consensus timeline.
Official Responses and Governance
The Ethereum Foundation and independent client teams have emphasized the importance of the community’s role in this transition. In a recent statement, core developers highlighted that "Glamsterdam is not merely an upgrade, but a structural refinement of Ethereum’s core."
Tim Beiko, a prominent figure in Ethereum’s governance, has consistently noted that network upgrades rely on "explicit opt-in." Because Ethereum is a decentralized, permissionless network, the success of the upgrade is dependent on the cooperation of node operators, validator services, and infrastructure providers.
Client teams, including those behind Geth, Nethermind, Prysm, and Teku, have already begun releasing compatible software versions. A critical point of contention during the design phase was the gas limit. Specifically, for validators running Prysm or Teku, the default gas limit is set to 60M post-activation. However, advanced users may opt for a 200M limit via specific configurations. This debate highlighted the tension between throughput and node-operating hardware requirements, ultimately resulting in the current flexible configuration model.
Implications for the Ecosystem
The impact of the Glamsterdam upgrade will be felt across several layers of the ecosystem:
For Stakers and Node Operators
The most immediate requirement is the technical update. Stakers must ensure that both their consensus layer beacon nodes and their execution layer clients are upgraded before the October 6 deadline. Failure to do so will result in the node falling out of sync with the network, leading to missed attestations or potential slashing risks for validators. The addition of the "Payload Timeliness Committee" (PTC) via ePBS also introduces new duties for validators, who must now attest to the availability of builder-provided data.
For Application Developers
Developers should be hyper-aware of the gas repricing. Many legacy smart contracts rely on hardcoded gas estimates or assumptions about the cost of storage. The "Glamsterdam Repricing Impact Guide" is an essential resource. Teams are encouraged to run their test suites against a local devnet configured with the Glamsterdam rules to ensure that gas estimation logic does not break or result in out-of-gas errors for their users.
For the Broader Network
The long-term implication is the maturation of Ethereum as a "rollup-centric" execution platform. By offloading complex block-building to specialized entities while keeping the validation simple, Ethereum is positioning itself to scale significantly without sacrificing the security of the L1. The shift toward parallel transaction validation is a precursor to future "Verkle tree" implementations and other state-sharding techniques that will eventually enable thousands of transactions per second.
Conclusion
Glamsterdam serves as a testament to the methodical, iterative nature of Ethereum’s development. By combining the lessons learned from previous upgrades like Fusaka with the long-awaited implementation of enshrined proposer-builder separation, the network is setting a new standard for decentralized efficiency.
As we approach the October 6, 2026, activation date, the focus remains on testing and coordination. The Ethereum ecosystem, through its bug bounty programs and extensive documentation, has created a robust framework for this transition. While the complexities of ePBS and block-level access lists are significant, the end result—a faster, more scalable, and more efficient Ethereum—is a clear objective that unites the community. For those wishing to follow the progress, the upcoming Sepolia activation will be the litmus test for the future of the Ethereum mainnet.
