Ethereum's Glamsterdam upgrade is now running on the Sepolia testnet. It brings protocol-level proposer-builder separation, block-level access lists, and a new gas pricing model that could change how blocks are built and validated.
Ethereum's core protocol just took a big step forward. The Glamsterdam upgrade launched on the Sepolia public testnet at 13:53:36 UTC on October 6, 2026, at epoch 353,024. This testnet run brings three major technical changes that could shift how blocks are built, checked, and priced. The main Ethereum network is not affected yet. Glamsterdam is not live on mainnet, and its future there depends on how these testnet trials go.
Key changes in block construction
The biggest change in Glamsterdam is enshrined proposer-builder separation (ePBS). This moves the link between block proposers and block builders into the protocol itself. Instead of using off-chain relays or outside coordination, the protocol now makes proposers include a builder's commitment to an execution payload. The builder then reveals the payload after. This setup aims to make block production smoother and could cut down on some types of manipulation or waste in how blocks are put together.
During the Sepolia test, the block gas limit was raised from 60 million to 200 million-over three times higher than before, but this setting is exclusive to Sepolia and not yet approved for mainnet.
Glamsterdam also adds block-level access lists. These lists track which accounts and storage slots each block touches, along with all state changes from every transaction. This lets Ethereum clients read state from disk and check transactions in parallel. It could make nodes run more efficiently and help avoid slowdowns as the network grows. The upgrade also changes gas pricing so costs better match the real computing and storage load on nodes, instead of sticking to old fee models.
Testnet deployment and validator impact
With Glamsterdam live on Sepolia, validators now have a public place to test higher block gas limits and the new protocol rules. Before the upgrade, developers released Prysm 7.2.1. This version sets the 200 million gas limit for blocks proposed by Sepolia validators. Without it, Prysm 7.2.0 would have kept the old 60 million limit. None of these changes are on Ethereum's mainnet yet. The Ethereum Foundation has not given dates for the Hoodi testnet or mainnet rollout.
Ethereum.org notes that ePBS also gives more time to spread block data across the network. The window grows from about 2 seconds to roughly 9 seconds. This could help with block propagation and lower the number of orphaned blocks. Community contributor Pooja Ranjan said the upgrade went live with 18 Core and 7 Other EIPs, showing just how much is changing under the surface.
Chainlink warned developers that transactions and other on-chain records on Sepolia could have failed for about 30 minutes before and after the upgrade; applications with strict gas limits were advised to provide extra buffer.
Scaling roadmap and next steps
Glamsterdam comes after last year's Fusaka upgrade and marks a key point in Ethereum's L1 scaling plans. The Ethereum Foundation says mainnet deployment is now expected in the fourth quarter, but there is no set date. Developers are already working on the next upgrade, with EIP-8141 planned for Hegotá in 2027. The Hoodi testnet is next for Glamsterdam, but its activation date is still up in the air.
These upgrades are part of Ethereum's ongoing push to solve scaling, efficiency, and decentralization problems. As reported earlier, protocol-level changes are now aimed at making decentralization a real advantage, not a drag on performance.
Technical and market context
Sepolia is a testnet and does not handle real value, but it is crucial for testing protocol upgrades. Testnet runs let developers and validators find bugs, performance issues, and surprises before anything hits mainnet, where billions of dollars are at risk. Glamsterdam's focus on parallel transaction checks and more accurate gas pricing could affect node costs, transaction fees, and network throughput if it moves to mainnet.
Ethereum's mainnet still handles millions of transactions daily. Public blockchain explorers show average daily gas use often tops 100 million units. Network upgrades that boost efficiency or change gas pricing can directly affect transaction costs, validator rewards, and the user experience, especially when demand is high.
Enshrined proposer-builder separation (ePBS) is a protocol-level rule that splits the work between block proposers, who suggest new blocks, and block builders, who put together the transaction payloads. By moving this process on-chain, ePBS tries to cut out off-chain relays and reduce some types of manipulation, like MEV (maximal extractable value) strategies that can hurt regular users. But how well ePBS works will depend on how validators, builders, and clients adjust to the new setup, and whether the changes bring new risks or slowdowns. As Ethereum keeps changing, finding the right balance between scaling, decentralization, and security is still a core challenge for both developers and users.
