Ethereum Glamsterdam Upgrade Goes Live on Sepolia Testnet

Ethereum's Glamsterdam upgrade activated on the Sepolia testnet at 1:53 pm UTC on October 6, 2026, marking one of the final major rehearsals before the changes reach the mainnet. The upgrade introduces enshrined proposer-builder separation, block-level access lists, and gas pricing adjustments designed to make the network more efficient and scalable. Ethereum community contributor Pooja Ranjan announced the activation in an X post.

The Ethereum Foundation detailed the upgrade plan in a September 28 blog post.

What is Glamsterdam?

Glamsterdam is Ethereum's next major protocol upgrade, following Fusaka which went live on December 3, 2025. It targets the network's layer-1 scaling roadmap by fundamentally reorganizing how blocks are created and verified. While Fusaka focused on foundational refinements like PeerDAS and blob scaling, Glamsterdam advances the Scale L1 and Scale Blobs objectives by enshrining the separation of duties between different network participants and introducing more efficient ways to handle data to prepare for high-throughput parallelization.

The headline feature is ePBS, or enshrined proposer-builder separation, specified in EIP-7732. This separates the heavy task of validating network transactions from the task of reaching consensus. The change expands the data propagation window from 2 seconds to roughly 9 seconds, unblocking Ethereum's ability to safely handle much higher transaction throughput and accommodate more data blobs for layer 2 networks. These improvements ensure Ethereum remains fast, affordable, and decentralized as it handles more activity, while keeping hardware requirements manageable for people running nodes at home.

Block-level access lists, or BALs, are designed to improve how block data and state access are handled. This makes it easier to track what is happening onchain while preventing technical hiccups as the network scales. The upgrade also enhances data discoverability and handles rising message sizes to prevent sync failures.

Gas pricing changes better reflect the actual cost of execution. All Ethereum transactions currently have a flat base gas fee, regardless of how simple or complex they are to process. Glamsterdam lowers the base fee for transactions, reducing the cost of a simple native ETH payment and making smaller transfers more affordable.

The upgrade also addresses staking withdrawal mechanics. Since the Pectra upgrade increased the maximum effective balance for validators from 32 ETH to 2,048 ETH, a technical loophole allowed high-balance validators to exit the network faster than smaller validators via the consolidation queue. Glamsterdam gives validator consolidations their own dedicated queue capacity and lets exit capacity scale with the total amount of ETH staked, rather than being capped at a fixed rate.

Why does the gas limit increase matter?

The gas limit increase matters because it directly tests whether Ethereum can handle significantly larger blocks without compromising network stability.

On Sepolia, the block gas limit is rising from approximately 60 million to 200 million, more than tripling the execution capacity per block. This is not just a number change. If higher block capacities can be sustained reliably on testnet, Ethereum gains greater block space to accommodate more transactions, stablecoin transfers, and other on-chain activity. The test will reveal whether the network's infrastructure, including validator clients and networking layers, can handle the increased load without degradation.

Ahead of the upgrade, the Ethereum validator client Prysm urgently released version 7.2.1 to fix an issue where the latest gas limit configuration was previously omitted. Validators using the new version will automatically generate blocks with a 200 million gas limit once Glamsterdam activates. Older versions that have not been manually reconfigured may continue to enforce the 60 million limit, potentially compromising the test results by creating a network with inconsistent block capacities.

What does this mean for ETH traders?

For ETH traders, the Sepolia activation is a signal that mainnet deployment is approaching, not a tradable event in itself.

The testnet fork does not affect mainnet ETH balances, staking, or transaction costs.

Successful testnet performance typically builds confidence ahead of mainnet activation. Traders should watch for the Hoodi testnet schedule announcement, which will provide a clearer timeline for the mainnet rollout.

The upgrade's gas pricing changes, if activated on mainnet, could lower the cost of simple ETH transfers. This would improve Ethereum's viability as a routine medium of exchange. Lower base fees for transactions reduce the cost of a simple native ETH payment, a change that has been discussed in the Ethereum community for several upgrade cycles.

What comes next?

After Sepolia, developers will determine the activation schedule for the Hoodi testnet.

Mainnet activation will follow once Hoodi testing is complete and client teams are satisfied with the results. Glamsterdam is expected to reach the mainnet in Q4 2026. After that, development of the next upgrade, Hegotá, is set to begin in earnest, with a target of 2027. Hegotá is expected to introduce fork-choice enforced inclusion lists, continuing Ethereum's path toward greater scalability and resilience.

Sepolia has served as Ethereum's primary testnet for major upgrade rehearsals. The network allows developers to test changes in a live environment with real economic incentives, albeit with valueless testnet ETH. Hoodi, the newer testnet, was introduced more recently and will serve as the final rehearsal environment before mainnet activation.

The Ethereum roadmap shows a consistent cadence of major upgrades. Pectra went live on May 7, 2025, followed by Fusaka on December 3, 2025. Each upgrade builds on the previous one's foundations, with Glamsterdam representing the most significant structural change to block production since the Merge.

What risks should traders watch?

Testnet upgrades can surface bugs that delay mainnet timelines.

The Prysm client fix ahead of Sepolia shows that even late-stage testing can uncover configuration issues that need urgent resolution. Validator client diversity remains a concern. If a significant portion of validators run outdated clients, the test may not accurately reflect mainnet conditions.

The 200 million gas limit is a testnet-only setting. Mainnet activation will require separate consensus among client teams, stakers, and the broader community. Past upgrades have shown that mainnet activation dates can shift based on testnet performance and community feedback.

The Ethereum Foundation has not announced a specific mainnet activation date.