The Ethereum network is set to undergo a significant upgrade, dubbed "Glamsterdam," building upon the foundational improvements introduced by the Fusaka upgrade. This latest iteration aims to further bolster Ethereum’s Layer 1 scaling roadmap by integrating enshrined proposer-builder separation (ePBS), block-level access lists (BALs), and refined gas pricing mechanisms. These advancements are designed to more accurately reflect the cost of execution and the network’s ongoing state growth, paving the way for increased throughput and a more robust decentralized ecosystem.
The Glamsterdam network upgrade is scheduled to activate on the Sepolia testnet on October 6, 2026, at epoch 353,024, slot 11,296,768, corresponding to 13:53:36 UTC. This precise timing marks a critical milestone in the multi-stage rollout of this complex upgrade. While the Sepolia activation provides a crucial testing ground, the dates for the Hoodi testnet and the ultimate mainnet deployment are still under deliberation by client teams, reflecting the careful and coordinated approach to implementing such a significant protocol change.
Node operators are urged to prepare for this transition by updating both their execution layer (EL) and consensus layer (CL) clients to versions compatible with the Glamsterdam upgrade well in advance of the activation date. Sepolia-compatible client releases will be systematically added to the designated client release tables as they are confirmed and made available. This ensures that the network’s participants are equipped with the necessary software to seamlessly integrate with the upgraded protocol.
Glamsterdam: A Synergistic Upgrade
Glamsterdam represents a powerful combination of the Amsterdam execution layer upgrade and the Gloas consensus layer upgrade. Its headline features, enshrined proposer-builder separation (ePBS) and block-level access lists (BALs), are poised to fundamentally alter how blocks are produced and validated. These changes are instrumental in enhancing Ethereum’s Layer 1 throughput, a key objective in the network’s long-term scaling strategy.
Enshrined Proposer-Builder Separation (ePBS)
At the core of the Glamsterdam upgrade is the introduction of enshrined proposer-builder separation (ePBS), detailed in EIP-7732. This mechanism integrates the separation between block proposers and builders directly into Ethereum’s consensus protocol. Previously, this separation relied on middleware, introducing potential points of centralization and trust. With ePBS, a proposer includes a builder’s commitment to an execution payload within the consensus block. Subsequently, the builder reveals this payload. Crucially, the protocol itself now handles the payment from the builder to the proposer, thereby reducing the reliance on third-party intermediaries and enhancing the trustlessness of the block production process.
Beyond streamlining the proposer-builder relationship, ePBS also creates a more efficient separation between consensus validation and execution validation. This separation grants validators more ample time to thoroughly validate execution payloads. A dedicated "payload timeliness committee" is established to attest to whether a builder has revealed its payload and if the associated blob data was made available in a timely manner. This added layer of validation and time for inspection is critical for maintaining network integrity and security.
For validator operators and teams responsible for maintaining builder infrastructure, this upgrade necessitates a review of new duties and interface protocols. Understanding these changes is paramount to ensuring a smooth transition and continued participation in the network.
Block-Level Access Lists (BALs)
EIP-7928 introduces block-level access lists (BALs), a groundbreaking feature designed to optimize block validation and state management. BALs meticulously record all accounts and storage locations accessed during the processing of a block, alongside any post-transaction state changes. This granular level of data recording offers significant advantages for node operators.
With BALs, Ethereum clients can achieve parallel reading of state from disk and parallel validation of transactions. This parallelization drastically reduces the time and computational resources required for block validation. Furthermore, BALs enhance the efficiency of computing state roots, a fundamental operation in maintaining the integrity of the blockchain.
The combined impact of ePBS and BALs is profound. They create a robust foundation for scaling Ethereum’s execution capacity while simultaneously ensuring that block validation remains practical and accessible for node operators, a critical factor in maintaining decentralization.
Gas Pricing and State Growth Adjustments
Glamsterdam also incorporates several crucial adjustments to gas accounting and pricing, aiming to align the cost of operations more closely with the actual resource utilization. EIP-8037 significantly increases and separately meters the cost associated with creating new state within the Ethereum Virtual Machine (EVM). This measure addresses the growing concern of state bloat by making state creation more expensive.
Complementing this, EIP-8038 revises the costs associated with accessing existing state. These changes, along with further modifications to intrinsic transaction gas, calldata costs, access list gas consumption, and overall block gas accounting, create a more accurate and sustainable economic model for network usage.
Application developers and protocol engineers are advised to thoroughly test their smart contracts and gas estimation mechanisms against these new rules. Contracts that rely on fixed gas stipends, hardcoded gas limits, or implicit assumptions about available gas may require modifications. A comprehensive "Glamsterdam repricing impact guide" has been made available to assist developers in identifying affected contracts and conducting necessary testing.
Developer and Validator Enhancements
Beyond the core scaling and efficiency upgrades, Glamsterdam also introduces a suite of improvements beneficial to developers and validators alike. These include the addition of ETH transfer logs, providing a more transparent and auditable record of value movements. A new slot-number opcode will offer developers greater flexibility in building time-sensitive smart contracts. The maximum contract size has been increased, allowing for more complex decentralized applications. A deterministic factory contract feature streamlines contract deployment, and new stack-manipulation instructions offer enhanced programming capabilities within the EVM.
On the consensus layer front, Glamsterdam brings forward-compatible data structures, ensuring smoother future upgrades. A significant security enhancement prevents slashed validators from proposing blocks, thereby safeguarding the network from malicious actors. Additionally, increased exit and consolidation churn mechanisms are introduced to improve the efficiency of validator set management.
Glamsterdam Specifications and EIPs
The Glamsterdam upgrade is formally tracked under EIP-7773, which serves as a central registry for all incorporated Ethereum Improvement Proposals. The following EIPs are slated for inclusion in the Glamsterdam upgrade:
- EIP-7732: Enshrined Proposer-Builder Separation
- EIP-7928: Block-Level Access Lists
- EIP-8037: Increased and Separately Metered Cost of State Creation
- EIP-8038: State Access Cost Adjustments
- EIP-7623: Increase Max Contract Size
- EIP-7692: Deterministic Factory Contract
- EIP-7594: ETH Transfer Logs
- EIP-7002: Execution Transition Cleanup
- EIP-7069: Remove
extcodehash‘s gas stipend - EIP-7774: Slot Number Opcode
- EIP-7735: New Stack Manipulation Instructions
In addition to these core protocol changes, EIP-7773 also encompasses supporting networking and informational EIPs that ensure seamless integration and operational efficiency across the Ethereum ecosystem.
Security and the Bug Bounty Program
The Ethereum Bug Bounty Program is now actively extended to cover the specifications and EIPs included in the Glamsterdam upgrade. As client implementations release versions supporting the Sepolia activation and are added to the official client release tables, they become eligible for security audits and bug bounty rewards. This proactive approach to security encourages rigorous testing and incentivizes the community to identify and report vulnerabilities, further bolstering the network’s resilience. Participants are encouraged to review the Ethereum Bug Bounty Program guidelines for detailed information on reward multipliers and reporting procedures.
Activation Timeline and Client Readiness
The agreed-upon deployment schedule, meticulously detailed in the Sepolia activation update to EIP-7773, outlines the following critical dates:
| Network | Epoch | Slot | UTC Time | UNIX Timestamp |
|---|---|---|---|---|
| Sepolia | 353,024 | 11,296,768 | 2026-10-06 13:53:36 | 1791294816 |
| Hoodi | TBD | TBD | TBD | TBD |
| Mainnet | TBD | TBD | TBD | TBD |
The activation on Sepolia on October 6, 2026, serves as a vital proving ground. The precise dates for the Hoodi testnet and the mainnet launch will be communicated separately once consensus is reached among client teams. This announcement specifically pertains to the Sepolia testnet and does not schedule the mainnet upgrade.
Client Releases and Node Operator Responsibilities
To ensure a smooth transition, node operators must update their clients to releases that explicitly confirm support for the Glamsterdam activation on Sepolia. The following tables will be regularly updated as new Sepolia-compatible client releases become available:
Consensus Layer Sepolia Releases:
(Placeholder for a table detailing CL client releases and versions)
When operating a validator, it is imperative that both the Consensus Layer Beacon Node and the Validator Client are updated to compatible versions.
Execution Layer Sepolia Releases:
(Placeholder for a table detailing EL client releases and versions)
Builder and validator tooling compatibility guidance will be provided as it is confirmed for Sepolia. Operators leveraging external block-building infrastructure are strongly advised to consult their respective upgrade instructions for Glamsterdam.
Frequently Asked Questions
How do Ethereum Network Upgrades Work?
Ethereum network upgrades are a coordinated effort that requires explicit opt-in from node operators. Client developers work collaboratively to implement protocol changes, and it is incumbent upon validators and non-staking nodes to update their software to align with the new rules. A node that fails to adopt the upgraded software will be unable to participate in the network post-activation. This decentralized coordination process is fundamental to the success of any network upgrade.
As an Ethereum Mainnet User or ETH Holder, is there anything I need to do?
No immediate action is required for Ethereum mainnet users or ETH holders. This announcement specifically pertains to the Sepolia testnet. A separate, comprehensive announcement will be made regarding the Glamsterdam activation on the mainnet.
As a Non-Staking Sepolia Node Operator, what do I need to do?
Non-staking node operators on the Sepolia testnet must update both their execution and consensus layer clients to releases that support the scheduled Sepolia activation before October 6, 2026, at 13:53:36 UTC. The client release tables will be updated as compatible versions are confirmed.
As a Sepolia Staker, what do I need to do?
Sepolia stakers must update their execution and consensus layer clients prior to the activation date. It is crucial to ensure that both the beacon node and validator client are updated to compatible versions. Validators should also review their client’s specific upgrade instructions, paying close attention to any new duties related to ePBS and any necessary adjustments to builder or validator tooling.
As a Hoodi or Mainnet Node Operator or Staker, what do I need to do?
At this time, no action is required for node operators or stakers on the Hoodi or mainnet networks in relation to this Sepolia announcement. Activation dates and compatible client releases for these networks will be communicated separately.
As an Application or Tooling Developer, what should I do?
Developers are encouraged to familiarize themselves with the EIPs scheduled for inclusion in Glamsterdam, as detailed in EIP-7773. After the Sepolia testnet activation, thorough testing of applications and smart contracts is recommended. Developers should assess the impact of changes to gas accounting, logs, opcodes, and client interfaces on their projects. Particular attention should be paid to the repricing impact guide, which will assist in identifying contracts reliant on fixed gas assumptions and in updating gas estimation mechanisms accordingly.
Why "Glamsterdam"?
The naming convention for Ethereum network upgrades follows a thematic approach. Execution layer upgrades are typically named after host cities of Devcon or Devconnect events, while consensus layer upgrades are named after stars. Glamsterdam is a portmanteau of "Gloas" (a consensus layer upgrade) and "Amsterdam," the host city of Devconnect in 2022, reflecting the combined nature of this significant protocol advancement.
