Ethereum Glamsterdam Upgrade Explained

Overview: What is the Glamsterdam upgrade?

Ethereum developers are planning a coordinated set of protocol changes informally referred to as “Glamsterdam.” The name reflects two linked upgrades across Ethereum’s execution and consensus layers. The initiative focuses on improving fairness, execution efficiency, and predictability while reducing certain centralization risks that have emerged around transaction ordering and block construction.

Although the final scope is still being finalized, core proposals under discussion include enshrined Proposer-Builder Separation (ePBS) and Block-level Access Lists. Developers have indicated a likely deployment window in 2026, following a series of earlier upgrades in 2025 that prepared the network for these next steps.

2025 context: why Glamsterdam matters now

The Ethereum roadmap throughout 2025 emphasized operational cost reductions for node operators and incremental protocol hardening. A notable upgrade earlier in 2025 reduced node resource requirements and prompted a reassessment of the block-production ecosystem.

Those developments sharpened attention on two market issues that Glamsterdam seeks to address:

• Maximal Extractable Value (MEV): revenue opportunities created by reordering, inserting, or censoring transactions remain economically significant and a source of contention.
• Centralization risk in block construction: off-chain relays and concentrated builder services have introduced trust assumptions that some in the community want to reduce.

Market participants in 2025 — from validators and builders to exchanges and DeFi protocols — watched these dynamics closely. Price and liquidity behavior around major rollouts in 2025 showed that governance and protocol-level fairness measures can materially influence user sentiment and operational planning.

Core components of Glamsterdam

ePBS (enshrined Proposer-Builder Separation) — EIP-7732

At the center of Glamsterdam is a proposal to enshrine Proposer-Builder Separation directly in Ethereum’s protocol. Under this approach, the roles of block builders (who assemble transactions into blocks) and proposers (validators who finalize blocks) are separated to limit any single participant’s ability to control transaction selection and ordering.

Key points of ePBS:

• Builders assemble and cryptographically seal block contents.
• Proposers select among sealed blocks principally based on economic criteria, such as payments, without being able to see or modify the enclosed transactions.
• The aim is to reduce on-chain opportunities for MEV extraction that depend on access to unsealed transaction data and to decrease reliance on centralized off-chain services.

By moving separation on-chain, ePBS is intended to create a more auditable and trust-minimized mechanism for block selection, replacing some of the ad hoc arrangements currently used in the ecosystem.

Block-level Access Lists — EIP-7928

Block-level Access Lists propose an execution-layer optimization that allows a block to declare, in advance, the accounts and storage areas it will access during execution. Rather than discovering this data incrementally, clients could preload or cache required state, improving execution efficiency.

Potential benefits include:

• Faster and more predictable block execution.
• Smoother gas estimation and potentially more stable transaction costs.
• A foundation for further performance optimizations and scaling techniques.

Taken together, ePBS and block-level access lists target both fairness in block inclusion and practical improvements in execution performance.

Why these changes aim to reduce MEV friction

MEV arises when validators, builders, or other actors can manipulate transaction ordering or inclusion to extract profit beyond standard fees. Current mechanisms that facilitate MEV often rely on off-chain coordination and visibility into mempool or builder-supplied bundles.

Glamsterdam’s approach tackles MEV from two angles:

• Limiting information asymmetry by sealing block contents prior to proposer selection, reducing predictability for opportunistic reordering or front-running.
• Improving execution predictability so automated strategies that hunt for profitable reorderings become harder to exploit consistently.

The combination is designed to make extractable opportunities harder to detect and less reliably profitable — thereby improving fairness for ordinary users and DeFi participants.

Operational and economic implications

Glamsterdam would reshape incentives across several ecosystem roles. Below are the main anticipated impacts.

Validators

• Validators would still receive rewards for proposing blocks, but their role in directly shaping transaction order would be constrained.
• Reliance on clear, auditable proposer-selection rules could change fee markets and require validators to adjust revenue strategies.

Builders and relays

• Builders will continue to play a central role in block assembly but will need to adopt cryptographic sealing workflows.
• Off-chain relays that currently mediate between builders and proposers may decline or evolve to provide sealed-bid coordination, with different trust assumptions.

DeFi protocols and users

• Improved predictability in execution and reduced MEV pressure could lower incidental slippage for large trades and limit the need for complex MEV-protection tooling.
• However, some forms of MEV mitigation that rely on private liquidity mechanisms may need to adapt to a changed block-construction landscape.

Node operators and client developers

• Block-level access lists could reduce computational burden per block by enabling better prefetch and caching strategies.
• Client implementations will need updates to support sealed block handling and access-list preloading, requiring coordination and testing across diverse node software.

Design trade-offs and open questions

While Glamsterdam addresses clear problems, it also introduces engineering and governance trade-offs that must be evaluated during specification and testnet phases.

Open questions include:

• How to enforce sealed-content guarantees without introducing new attack vectors or excessive complexity.
• Whether enshrined separation will unintentionally concentrate power in new intermediaries unless carefully specified.
• How block-level access lists will interact with privacy-focused techniques and future scaling layers.

These uncertainties underscore why the upgrade window extends into 2026: rigorous testing, community review, and multi-client implementations are essential before mainnet adoption.

Potential timeline and rollout considerations

Developers have not yet finalized the complete list of EIPs that will be included in Glamsterdam. The current expectation is for continued specification work, community feedback, and testnet deployments through 2025 and into 2026.

A typical rollout path will include:

• Specification refinement and formal EIP acceptance procedures.
• Client-level implementation across multiple node software projects.
• Testnet activation with coordinated upgrade testing and bug bounties.
• Mainnet deployment once broad client support and sufficient testing have been achieved.

Market outlook: what participants should watch

From a market perspective in 2025–2026, stakeholders should monitor several indicators that will signal readiness and potential impact:

• Testnet performance metrics: execution time, block validation latency, and error rates.
• Adoption rates among major node implementations and validator clients.
• Changes in MEV revenue flows reported by analytics providers and protocol teams.
• Behavioral shifts in relays and builder services as they adapt to sealed-block markets.

Traders, liquidity providers, and protocol teams should also consider contingency plans for the upgrade window, including testing contracts on compatible testnets and tracking client release schedules.

Conclusion: measured change with broad implications

Glamsterdam represents a significant step in Ethereum’s evolution: a move to inscribe fairness-oriented mechanisms into core protocol logic while optimizing execution performance. If implemented carefully, the upgrade could reduce certain types of MEV, improve execution predictability, and provide a stronger foundation for future scaling work.

At the same time, the shift will require coordinated effort from client teams, validators, builders, and other ecosystem participants. The full impacts will depend on implementation details, testing outcomes, and how market participants adapt their business models. For market observers in 2025 and into 2026, the focus will be on technical readiness, economic rebalancing, and the practical effects on transaction costs and trading behavior.

MEXC will continue to monitor these developments and provide updates as specifications mature and timelines are clarified.

Disclaimer: This post is a compilation of publicly available information.
MEXC does not verify or guarantee the accuracy of third-party content.
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