Ethereum's Glamsterdam Upgrade Hits Sepolia on Oct. 6

Published October 4, 2026, 09:05 UTC

Ethereum's next major network upgrade, Glamsterdam, is scheduled to activate on the Sepolia test network on October 6, 2026 at 13:53:36 UTC. The Ethereum Foundation's announcement says dates for the Hoodi testnet and for mainnet have not yet been decided.

Not a mainnet upgrade

The announcement is explicit: ETH holders and mainnet users do not need to do anything. This activation covers Sepolia only, and a separate announcement will cover mainnet. Sepolia node operators and stakers must update both execution and consensus clients before the fork. Sepolia is a public test network, and its test ETH has no market value (general background).

What Glamsterdam changes

Glamsterdam follows the Fusaka upgrade and combines the Amsterdam execution-layer upgrade with the Gloas consensus-layer upgrade. According to the Foundation, the headline changes are:

• Enshrined proposer-builder separation (EIP-7732): moves the handoff between block proposers and specialised builders into the protocol, reducing reliance on trusted middleware.
• Block-level access lists (EIP-7928): record the accounts and storage a block touches, so clients can read state and validate transactions in parallel.
• Gas repricing (EIP-8037, EIP-8038): adjusts costs to better reflect the resources used when creating and accessing state.

The Foundation says these changes support greater throughput on Ethereum's base layer. It also lists smaller items, such as ETH transfers emitting a log and a higher maximum contract size.

What developers should watch

The Foundation warns that contracts relying on fixed gas stipends, hardcoded gas limits or assumptions about remaining gas may need changes, and it points developers to a repricing impact guide. Its bug bounty programme is now active for Glamsterdam specifications. The Foundation also notes that Prysm 7.2.0 and Teku 26.9.1 default to a 60M gas limit after activation, so validators wanting a 200M limit must configure it explicitly.

EtherWorld's summary of a developer call (ACDE #246, September 24) reports that developers agreed to schedule signalling toward a 200 million gas limit on Sepolia alongside the fork, as a deliberately demanding test. The same summary says adversarial testing on Devnet 8 produced valid workloads that took unusually long to execute, with developers discussing blocks that could require eight seconds or more under some attack patterns. Developers chose the demanding test despite those concerns, arguing Sepolia should expose problems before similar conditions reach mainnet.

What comes next

According to Cointelegraph, developers are targeting 2027 for Hegotá, the upgrade expected to follow Glamsterdam. It also reported that co-founder Vitalik Buterin said Hegotá could be Ethereum's last "normal" fork before work shifts toward areas such as recursive STARKs, formal verification and quantum-safe cryptography. Neither the Foundation's announcement nor the developer call notes we reviewed sets a mainnet date.

Why it matters

Testnet forks let teams find problems before real value is at stake. How Sepolia behaves, including the higher gas-limit test, will inform later decisions. For background on how Ethereum is scaling, see What Are Layer-2 Rollups?

This article is news reporting and is not investment advice.

Sources

• Ethereum Foundation, Glamsterdam Testnet Announcement (Sept. 28, 2026; the URL carries an earlier date)
• Cointelegraph, Ethereum schedules Glamsterdam upgrade on Sepolia for Oct. 6 (Sept. 29, 2026)
• EtherWorld, Ethereum Protocol Update: ACDE #246 (Sept. 24, 2026)