Ethereum Glamsterdam Hits Sepolia Oct 6: When Is Mainnet?

Ethereum has set a date for the Glamsterdam upgrade on its Sepolia testnet. The fork will activate at epoch 353,024, slot 11,296,768, on October 6, 2026, at 13:53:36 UTC. That gives developers and node operators a firm testnet milestone, but not a mainnet countdown.

Glamsterdam is the next step in Ethereum’s Layer 1 scaling roadmap after Fusaka. It combines two upgrades: Amsterdam on the execution layer and Gloas on the consensus layer. Its main changes target how the network builds blocks, validates transactions, and prices the resources that the state requires.

🚨𝗟𝗔𝗧𝗘𝗦𝗧: Ethereum’s Glamsterdam upgrade is set to go live on the Sepolia testnet on October 6, marking the next major testing step before a broader rollout. pic.twitter.com/AfeaExTP3b

— DustyBC Crypto (@DustyBC) September 29, 2026

How Will ePBS Change Ethereum Block Building?

The headline change is enshrined proposer-builder separation, or ePBS, introduced through EIP-7732. It moves the handoff between block proposers and builders directly into Ethereum’s consensus protocol.

Here is how it works. A proposer commits to a builder’s execution payload, and the builder reveals that payload later. The protocol itself handles payment to the proposer, cutting reliance on trusted middleware. A payload timeliness committee then confirms whether the builder revealed its payload and blob data on time.

The change also splits consensus validation from execution validation. That gives validators more time to check payloads.

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What the Test Means for Ethereum’s Scaling Roadmap

The October 6 fork is a concrete development catalyst, not evidence that the upgrade has already improved Ethereum’s throughput or lowered costs. Those outcomes depend on implementation and testing; the announcement establishes the protocol changes being evaluated, not realized network or market results.

For application developers, the immediate implication is to test contracts and gas estimates against the revised rules. The source flags contracts that rely on fixed gas stipends, hardcoded gas limits, or assumptions about remaining gas as potentially needing changes. That practical focus on evaluating protocol behavior through testing also runs through Ethereum’s other testnet-based scaling evaluations.

The Ethereum.org roadmap separately places the expected mainnet upgrade in Q4 2026, while stating that the date is not confirmed. Glamsterdam is part of a longer-term effort to increase Ethereum’s capacity while managing execution and state growth. Its broader design also connects to the network’s evolving role as a settlement layer, including approaches that scale computation beyond the base layer. Learn more in Ethereum’s long-term Layer 1 roadmap.

Client Readiness Comes Before the Next Date

⚡️Ethereum just casually hits 42,000+ TPS daily peak

With the upcoming Glamsterdam, this speed will only increase!$ETH is COMING pic.twitter.com/giWPYLTzdM

— Ethprofit.eth 🦇🔊 (@Ethprofit) September 30, 2026

Sepolia node operators must update both execution-layer and consensus-layer clients before activation, and should use only releases whose notes explicitly confirm support for the scheduled fork. Listed consensus releases include Lodestar 1.49.0, Nimbus 26.9.0, Prysm 7.2.0, and Teku 26.9.1; execution releases include Besu 26.9.0, Erigon 3.7.0, go-ethereum 1.17.6, Nethermind 2.0.0, and Reth 2.7.0.

Builder and validator tooling compatibility guidance is still to be added, as it is confirmed for Sepolia, making infrastructure readiness another item to monitor. Client teams will announce Hoodi and mainnet activation times once decided; until then, October 6 is a firm Sepolia test date, while the mainnet timeline remains an unconfirmed roadmap expectation.

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