The Ethereum network is poised for a significant evolution with the upcoming "Glamsterdam" upgrade, a pivotal development that follows the successful "Fusaka" upgrade. This latest iteration aims to further advance Ethereum’s Layer 1 scaling roadmap by introducing several key enhancements, including enshrined proposer-builder separation (ePBS), block-level access lists (BALs), and refined gas pricing mechanisms designed to more accurately reflect the costs associated with execution and state growth. The Glamsterdam upgrade is currently 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. While activation dates for the Hoodi and mainnet environments are yet to be determined, the Sepolia testnet serves as a crucial proving ground for these advanced features.
Background and Context: The Pursuit of Ethereum Scalability
The Ethereum network, since its inception, has been on a continuous journey to enhance its scalability, security, and efficiency. The transition to Proof-of-Stake (PoS) with "The Merge" marked a monumental step, but the quest for higher transaction throughput and reduced fees remains a paramount objective. The "Fusaka" upgrade laid critical groundwork, and Glamsterdam builds upon this foundation by addressing fundamental aspects of block production and validation. This upgrade represents the culmination of extensive research, development, and community consensus aimed at making Ethereum more robust and accessible for a wider range of applications and users. The naming convention itself, combining "Gloas" (a consensus layer upgrade, likely named after a star) and "Amsterdam" (the host city of Devconnect in 2022), reflects the collaborative and geographically diverse nature of Ethereum’s development community.
Key Innovations within the Glamsterdam Upgrade
Glamsterdam represents a strategic integration 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 designed to fundamentally alter how blocks are constructed and validated, paving the way for increased Layer 1 throughput.
Enshrined Proposer-Builder Separation (ePBS): A Paradigm Shift in Block Production
At the heart of the Glamsterdam upgrade is the introduction of enshrined proposer-builder separation (ePBS), formalized by EIP-7732. This innovation directly integrates the separation between block proposers and builders into Ethereum’s consensus protocol. Previously, a complex ecosystem of middleware facilitated the communication and payment mechanisms between proposers (validators) and builders (entities that construct blocks). ePBS streamlines this process by allowing a proposer to include a builder’s commitment to an execution payload directly within the consensus layer. The builder then reveals this payload, along with the corresponding blob data. Crucially, the protocol itself now handles the payment to the proposer, significantly reducing the reliance on trusted third-party intermediaries.
This separation also brings a critical enhancement: the decoupling of consensus validation from execution validation. This provides validators with more ample time to scrutinize execution payloads. A dedicated "payload timeliness committee" will attest to whether a builder has revealed its payload and if the associated blob data was made available within the stipulated timeframe. For validator operators and teams managing builder infrastructure, this necessitates a thorough review of new duties and interfaces to ensure seamless integration with the upgraded protocol.
Block-Level Access Lists (BALs): Optimizing State Access and Validation
Complementing ePBS, Block-Level Access Lists (BALs), introduced by EIP-7928, represent another significant advancement. BALs enforce the recording of all accounts and storage locations accessed during the creation of a block, alongside any post-transaction state changes. This granular tracking provides a detailed map of state interactions within each block.
The implications of BALs are far-reaching. They empower clients to read state from disk in a parallelized manner, thereby accelerating transaction validation. Furthermore, the ability to validate transactions in parallel and compute state roots more efficiently contributes directly to the overall scalability and performance of the network. Together, ePBS and BALs create a robust foundation for scaling Ethereum’s execution capacity while ensuring that block validation remains a practical and manageable task for node operators.
Gas Pricing and State Growth: A More Accurate Reflection of Costs
Glamsterdam also addresses the intricate economics of Ethereum by adjusting gas accounting to more accurately reflect resource utilization. EIP-8037 mandates an increase and separate metering of the cost associated with creating state. Concurrently, EIP-8038 revises the costs associated with accessing state. These changes are further supplemented by modifications to intrinsic transaction gas, calldata costs, access lists, and overall block gas accounting.
These repricing mechanisms are designed to incentivize more efficient resource management on the network. For application developers, this necessitates thorough testing of their smart contracts and gas estimation logic against the new rules. Contracts that rely on fixed gas stipends, hardcoded gas limits, or make assumptions about the amount of remaining gas may require modifications to function correctly post-upgrade. A dedicated "Glamsterdam repricing impact guide" is available to assist developers in identifying affected contracts and conducting necessary testing.
Developer and Validator Enhancements
Beyond the core scaling features, Glamsterdam incorporates a suite of improvements aimed at benefiting developers and validator operators. These include the introduction of ETH transfer logs, a slot-number opcode for more precise temporal referencing, an increased maximum contract size to accommodate more complex applications, a deterministic factory contract for predictable contract deployment, and new stack-manipulation instructions to enhance smart contract efficiency.
On the consensus layer front, changes include forward-compatible data structures to ensure smoother future upgrades, provisions to exclude slashed validators from proposing blocks to maintain network integrity, and an increased churn rate for exits and consolidations to improve validator management efficiency.
Technical Specifications and EIPs
The Glamsterdam upgrade is tracked under EIP-7773, which serves as a central registry for all included Ethereum Improvement Proposals. Key EIPs slated for inclusion in this upgrade are:
- EIP-7732: Enshrined Proposer-Builder Separation (ePBS)
- EIP-7928: Block-Level Access Lists (BALs)
- EIP-8037: Increased and Separately Metered State Creation Cost
- EIP-8038: Revised State Access Costs
Additional supporting EIPs related to networking and informational aspects are also part of the comprehensive upgrade package. The full list of scheduled EIPs provides a detailed technical roadmap for the changes being implemented.
Security Considerations and Bug Bounty Program
The Ethereum Bug Bounty Program has been activated for the Glamsterdam specifications and associated EIPs. Client implementations become eligible for bug bounty rewards as soon as their release versions are officially listed as supporting the Sepolia fork. This proactive approach underscores Ethereum’s commitment to robust security, encouraging developers and security researchers to identify and report potential vulnerabilities. The program offers substantial rewards and clear reporting requirements, incentivizing the community to contribute to the network’s security.
Activation Schedule and Node Operator Responsibilities
The agreed-upon deployment schedule for Glamsterdam is as follows:
- Sepolia Testnet: Activation is set for October 6, 2026, at 13:53:36 UTC (epoch 353,024, slot 11,296,768).
- Hoodi Testnet: Activation date and time are TBD.
- Mainnet: Activation date and time are TBD.
For Sepolia, node operators must ensure their execution and consensus layer clients are updated to compatible versions before the activation time. Client releases supporting the Sepolia fork will be progressively added to the designated release tables. It is imperative that operators consult the release notes of their chosen clients to confirm explicit support for the Glamsterdam upgrade on Sepolia.
Consensus and Execution Layer Client Releases
Specific client versions are being finalized and will be announced as they become available. For instance, Prysm version 7.2.0 supports the Sepolia fork but defaults to a 60 million gas limit post-activation. Validators aiming for a 200 million gas limit will need explicit configuration. Similarly, Teku version 26.9.1 also supports the Sepolia fork but requires explicit configuration for a 200 million gas limit. Operators are strongly advised to review the detailed release notes and documentation for their specific client software.
Implications for Users and Developers
For most Ethereum mainnet users and ETH holders, the Glamsterdam upgrade on Sepolia requires no direct action. This announcement pertains to testnet operations. A separate, comprehensive announcement will be made prior to the mainnet activation.
However, for non-staking Sepolia node operators, the requirement is clear: update both execution and consensus layer clients before the October 6, 2026 deadline. Stakers on Sepolia must similarly update their beacon node and validator client software, paying close attention to any new ePBS duties or tooling adjustments.
Application and tooling developers have a more involved role. They are urged to familiarize themselves with the EIPs scheduled for Glamsterdam, test their applications on the Sepolia testnet post-activation, and assess the impact of changes to gas accounting, logs, opcodes, and client interfaces. The repricing impact guide will be a critical resource for identifying and rectifying contracts that may be adversely affected by the new gas economics.
Broader Impact and Future Outlook
The Glamsterdam upgrade represents a significant stride towards achieving Ethereum’s long-term scaling objectives. By enhancing block production efficiency through ePBS and optimizing state access with BALs, Ethereum is better positioned to handle a greater volume of transactions at a potentially lower cost. The refined gas pricing mechanisms also contribute to a more sustainable and economically sound network.
The successful activation on Sepolia will pave the way for the subsequent rollout on Hoodi and eventually the mainnet, marking a new era for Ethereum’s Layer 1 scalability. This upgrade, along with ongoing developments in Layer 2 scaling solutions, collectively reinforces Ethereum’s position as a leading platform for decentralized applications and innovation. The commitment to iterative improvements and community-driven development remains a cornerstone of Ethereum’s evolution, ensuring its continued relevance and growth in the blockchain ecosystem.
