Ethereum cleared a quiet but important milestone in June 2026. The Glamsterdam upgrade entered its final devnet phase as the last step before public testnets and a mainnet target of H2 2026, according to Ethereum’s official Glamsterdam roadmap page.
Fusaka shipped in December 2025 as the upgrade that made blobs cheaper for layer-2s. Glamsterdam is the upgrade that targets base-layer speed rather than just data cost.
Most coverage states that Glamsterdam scales Ethereum. That description is true but lacks the mechanical detail a technical reader needs. The changes under the hood involve specific protocol numbers with measurable parameters.
The Glamsterdam roadmap sits at the center of Ethereum L1 scaling plans for 2026. The upgrade bundles execution-layer changes with consensus-layer separation under one coordinated fork.
The 2-second hot path bottleneck and the 9-second propagation fix
Today a validator has roughly 2 seconds to broadcast a block, execute transactions, and reach network agreement. That tight window is the invisible ceiling on Ethereum’s throughput. It limits how large blobs for layer-2s can grow.
Blobs are data containers that layer-2 rollups post to Ethereum for data availability. The cheaper blob space from Fusaka in December 2025 lowered L2 costs, but blob size still faced the 2-second execution bound.
It also explains why raising the gas limit is not a free adjustment. The 2-second constraint binds every other scaling lever on the base layer.
Glamsterdam introduces Enshrined Proposer-Builder Separation under EIP-7732, as detailed on the protocol’s Glamsterdam specification page. The change splits the job of proposing a consensus block from building the execution payload. It bakes the hand-off into the protocol instead of relying on third-party middleware such as MEV-Boost.
The practical result is a propagation window that opens from about 2 seconds to roughly 9 seconds. That 7-second gain is concrete and large. A 9-second window is 4.5 times longer than the 2-second window that exists today.
The longer window lets Ethereum carry more data per block. More blobs for L2s fit inside the larger window. More headroom exists before the network reaches congestion points that force fee spikes.
Block-Level Access Lists move Ethereum to parallel execution
The second change is Block-Level Access Lists under EIP-7928. The Glamsterdam roadmap documentation describes how Ethereum currently processes transactions one at a time in a serial model. The serial model exists because the network cannot know in advance which accounts a transaction touches.
Two transactions hitting the same account at once would collide under serial rules. Block-Level Access Lists act as a map that removes that blind spot. Before execution, the block declares exactly which parts of the database every transaction will touch.
Validators can then read data for many transactions in parallel. They group the non-overlapping transactions together for concurrent processing. This structural shift moves Ethereum off serial execution toward genuine parallel processing for the first time at the base layer.
A side benefit is faster node sync for operators. A new node can copy final results instead of replaying every transaction from history. A companion upgrade named eth/71 under EIP-8159 updates the peer-to-peer layer so nodes share those access lists across the network.
Without EIP-8159, the BALs defined in EIP-7928 would stay isolated on a single machine. The two EIPs ship as a paired dependency inside the Glamsterdam bundle. This pairing is what makes the parallel model functional across distributed validators.
Fee impact: EIP-2780 and gas limit headroom
Glamsterdam includes EIP-2780 for reduced intrinsic transaction gas. This lowers the base cost of a simple ETH transfer at the protocol level. The parallel-execution work from EIP-7928 paves the way for higher overall gas limits as capacity grows.
As capacity grows, per-transaction costs should drop for everyday users. The precision matters when setting expectations. This is L1 getting cheaper by a measurable margin and more capable in throughput.
It is not Ethereum becoming a penny-chain with sub-cent fees overnight. Near-zero fees remain an L2 story on rollups. Glamsterdam makes the L2s’ underlying data layer cheaper to use, which compounds across the ecosystem as blob space expands.
For example, a rollup paying for blob space benefits when the base layer carries more data per block. Specifically, the ePBS window growth from 2 seconds to 9 seconds allows larger blob counts per slot without risking consensus failure.
Engineering risks outside the headline
Three risks require attention because none of the gains are free. The first is staking pool architecture change. EIP-7732 requires pools to enable trustless monitoring of builders who assemble payloads.
Pools that skip the update could see degraded validator performance and missed attestations. This is operational work the ecosystem must complete before the H2 2026 target. The second risk is status mismatch between devnet and mainnet.
Glamsterdam is in final devnet as of June 2026, not shipped to production. The H2 2026 mainnet date is an internal working target on the Ethereum roadmap site subject to devnet results. Protocol dates slip when testnets surface bugs.
The third risk is state-growth economics that cut both ways. The sustainability EIPs numbered 8037 and 8038 increase state-creation gas costs for developers. Deploying large contracts becomes more expensive in some cases to keep node hardware requirements sane.
Developers will feel that cost directly on deployment. Some will object to the higher upfront gas spend. The trade protects long-term node operator accessibility against chain bloat.
What Glamsterdam means for passive ETH holders
If you hold ETH and do nothing, the upgrade asks nothing of you at the user level. Existing smart contracts keep working without modification. Wallets keep working with no action required from owners.
The upgrade is opt-in at the protocol level where validators adopt it. Users lift no finger during the transition. What you watch is whether Ethereum keeps its fast, cheap, decentralized promise as activity grows.
Glamsterdam is the most serious attempt yet to keep all three properties intact. The June 2026 devnet milestone means it is no longer just a roadmap slide for conference decks. The items to track are specific and observable.
Testnet activation dates will post to the official roadmap over the coming months. Major staking pools must ship ePBS monitoring updates before mainnet to avoid performance loss. Those two items decide if H2 2026 delivers a modern-feeling L1 to end users.
Frequently asked questions about the Glamsterdam upgrade
When is Glamsterdam expected on mainnet?
The primary roadmap sets a target of H2 2026 for mainnet activation. The final devnet began in June 2026 as the last pre-testnet stage. The date is a working target tied to devnet outcomes, not a fixed release committed in code.
Does ePBS under EIP-7732 remove MEV-Boost entirely?
It bakes proposer-builder separation into the protocol itself rather than leaving it to external software. That reduces reliance on third-party middleware such as MEV-Boost for the separation hand-off. The roadmap describes this model as enshrined rather than externally operated.
Will Block-Level Access Lists break existing smart contracts?
No. EIP-7928 changes how execution is scheduled and parallelized across validators. It does not alter execution semantics or state outcomes. Contracts deployed on the current chain continue to function after the upgrade without changes.
How much does the propagation window actually change with ePBS?
It moves from about 2 seconds to roughly 9 seconds under EIP-7732. That is a 7-second increase equal to 4.5 times the prior window length. The gain is what enables larger blocks and more blob space per slot.
What do higher state-creation gas costs under EIP-8037 and 8038 mean for users?
End users sending ETH transfers see lower costs from EIP-2780 instead. The state-creation increases hit contract developers deploying large storage footprints. The measure protects node hardware requirements from unbounded growth.
Why does Glamsterdam enter final devnet before public testnets?
The final devnet in June 2026 lets client teams rehearse the full EIP bundle off public chains. Public testnets follow only after the devnet shows stable ePBS and BAL behavior under the 9-second window.
Bottom line: ETH holders should track the Glamsterdam testnet activation dates on the official roadmap and confirm by H2 2026 that their staking pool has shipped ePBS monitoring under EIP-7732, since the upgrade itself needs no wallet action but depends entirely on validator-side readiness for the 2-second-to-9-second propagation shift to reach mainnet safely.
