Ethereum Glamsterdam Upgrade: How ePBS Will Reshape Block Production

Ethereum is preparing for its most consequential upgrade since The Merge. Glamsterdam, the network's next hard fork, will enshrine Proposer-Builder Separation (ePBS) directly into the protocol layer -- a change that restructures how blocks are built, proposed, and validated across the entire network. With devnet-4 already running multi-client tests and mainnet deployment targeted for late 2026, every developer building on Ethereum needs to understand what is changing and why it matters.

What Is Glamsterdam?

Glamsterdam is the codename for Ethereum's next consensus-layer hard fork, formally defined under EIP-7773. Following the Pectra upgrade that shipped earlier in 2025, Glamsterdam represents a focused effort to solve one of Ethereum's most persistent structural problems: the relationship between block proposers (validators) and block builders.

Today, validators rely on external relay infrastructure like MEV-Boost to outsource block construction to specialized builders. This system works, but it introduces trust assumptions, centralization risks, and a dependency on off-protocol software that the Ethereum protocol itself cannot enforce or guarantee. Glamsterdam changes that by moving the proposer-builder separation mechanism into the protocol itself.

EIP-7732: Enshrined Proposer-Builder Separation Explained

At the heart of Glamsterdam is EIP-7732, the Enshrined Proposer-Builder Separation proposal. Under the current system, a validator proposes a complete block -- including all transaction ordering and MEV extraction decisions. With ePBS, the block production process splits into two distinct on-chain roles.

The proposer selects a builder's bid and commits to it on-chain by publishing a signed commitment. The builder then reveals the full block contents, and the network validates that the builder's payload matches the commitment. This entire handshake happens at the protocol level, eliminating the need for trusted relays.

The technical mechanism introduces a new beacon chain message type -- the execution payload envelope -- that separates the consensus attestation from the execution payload. Validators attest to the proposer's commitment first, and then separately verify the builder's revealed payload. This two-phase process means that even if a builder fails to reveal their block, the chain can still advance without disruption.

Why ePBS Matters: Solving MEV Centralization

Maximal Extractable Value (MEV) has become one of Ethereum's most debated issues. Today, a small number of sophisticated builders win the majority of block auctions, concentrating significant power in a handful of entities. Research from the Flashbots Collective estimates that ePBS could reduce MEV-related losses for ordinary users by up to 70 percent, primarily by creating a more competitive and transparent auction mechanism.

By moving block building auctions on-chain, ePBS removes the trust assumptions baked into the current relay system. Builders no longer need to trust relays not to steal their transaction bundles, and proposers no longer need to trust that relays will deliver valid blocks. The protocol itself enforces the rules, creating a level playing field that lowers the barrier to entry for new builders.

For application developers, this translates into more predictable transaction inclusion, reduced sandwich attack exposure, and a more stable gas market. DeFi protocols that currently lose value to MEV extraction stand to benefit the most, but the improvements cascade across every application that submits transactions to Ethereum.

Devnet Progress: Where Glamsterdam Stands Today

As of early June 2026, the Ethereum Foundation's ethPandaOps team has progressed through four development network iterations. Devnet-4, the most recent, is running multi-client consensus with several execution and consensus client teams participating. The iterative devnet approach follows the same battle-tested methodology used for previous upgrades like Dencun and Pectra.

Key milestones achieved so far include stable ePBS block production across multiple client implementations, successful builder-proposer handshake validation under simulated MEV conditions, and initial benchmarking of the two-phase attestation mechanism's impact on slot timing. The Ethereum Foundation's Checkpoint 9 report from April 2026 confirmed that ePBS is the primary focus for the consensus layer, while the subsequent Hegota upgrade will address execution-layer improvements.

What Changes for Developers

If you are building applications on Ethereum, Glamsterdam introduces several shifts worth preparing for. Transaction ordering guarantees become stronger under ePBS, meaning that applications relying on specific inclusion timing may see more consistent behavior. The two-phase block structure also opens the door for new preconfirmation mechanisms that could eventually give users faster finality signals.

Smart contract developers will not need to modify existing contracts -- ePBS operates at the consensus layer and does not change the EVM. However, infrastructure providers, wallet developers, and anyone running transaction submission pipelines should monitor the devnet progress closely. The way transactions flow from mempool to block inclusion is fundamentally changing, and tooling built on MEV-Boost assumptions will need to adapt.

For teams building across multiple chains or deploying to Ethereum L2s, the ePBS architecture also sets the foundation for more efficient cross-layer block building. As rollups increasingly rely on Ethereum for data availability and settlement, a protocol-native builder market creates new possibilities for sequencer-proposer coordination. If you are evaluating your infrastructure stack for these changes, thirdweb offers developer plans that scale with your project and help you ship across chains without managing low-level protocol complexity -- check out thirdweb.com/pricing for details.

The Bigger Picture: Glamsterdam in Ethereum's Roadmap

Glamsterdam is one piece of a broader 2026 roadmap that the Ethereum Foundation outlined earlier this year. While ePBS addresses the consensus layer's builder market, the follow-up Hegota upgrade is expected to tackle execution-layer concerns including gas limit adjustments and state management improvements. Together, these upgrades represent Ethereum's push toward what Vitalik Buterin has described as the network's mature infrastructure phase.

The post-quantum key registry work happening in parallel -- covered in a separate initiative by Ethereum researchers -- adds another dimension to the network's long-term security posture. Combined with the ongoing ZK-proof integration for block validation, Ethereum is simultaneously hardening its consensus mechanism, future-proofing its cryptography, and scaling its data availability layer.

Timeline and What to Watch

Based on current devnet progress, the Ethereum community is targeting a mainnet Glamsterdam deployment in late 2026, likely Q3 or early Q4. The path from devnet-4 to testnet deployment typically takes several months, with the Goerli and Sepolia testnets expected to fork first.

Key milestones to watch include the transition from devnet to public testnet, the All Core Devs consensus calls where final inclusion decisions are made, and any changes to the EIP-7773 meta specification that could add or remove proposals from the fork. The ACDC-178 call from May 2026 confirmed that EIP-7732 remains the centerpiece, but additional smaller EIPs may be bundled depending on client team readiness.

Conclusion

Glamsterdam marks a turning point for Ethereum's block production architecture. By enshrining proposer-builder separation at the protocol level, the upgrade eliminates trusted intermediaries, reduces MEV centralization, and creates a more transparent market for block construction. For developers, the practical impact is better transaction inclusion guarantees, a more predictable gas market, and a foundation for future innovations like preconfirmations and cross-layer block building.

Whether you are running a DeFi protocol, building a wallet, or deploying smart contracts, now is the time to follow the devnet progress and start evaluating how ePBS will affect your transaction submission pipeline. The upgrade is coming, and the builders who prepare early will have the clearest advantage.