Ethereum core developers have tentatively scheduled the Glamsterdam upgrade for activation on the Sepolia testnet at 13:53 UTC on October 6, 2026. The decision was made during All Core Developers Consensus call #186, with the agreed Sepolia epoch set at 351232. The date replaces an earlier September 28 target and remains explicitly conditional: developers have not yet completed a stable Glamsterdam transition on a private devnet.
The next major private testing milestone is now Glamsterdam-Devnet-11, expected to launch on September 14, replacing earlier plans centered on Devnet-10. Ethereum protocol researcher Christine D. Kim noted that “all eyes are on the launch of Glam-Devnet-11 next Monday, not Devnet-10.”
Earlier devnets exposed serious faults. Devnet-8 revealed a consensus-layer problem involving blocks that repeated a parent hash, which Ethereum Foundation developer operations engineer Stefan Starflinger said could “get the whole network to stop.” Devnet-9 then suffered non-finality with roughly 1,000 validators, while execution-side testing found an implementation issue related to EIP-8037, a multidimensional gas model separating state-creation costs from normal execution costs.
Glamsterdam’s main features include enshrined proposer-builder separation (ePBS) and Block-Level Access Lists (BALs). ePBS moves validator-block builder relationships directly into Ethereum consensus, reducing reliance on trusted third-party software. BALs identify which parts of Ethereum’s state a block accesses, laying groundwork for parallel execution and disk reads. The upgrade also includes gas repricings supporting roughly a 200 million gas floor, increases the maximum deployed contract size from 24 KiB to 64 KiB, and raises maximum initcode from 48 KiB to 128 KiB.
The Ethereum Foundation has launched Platåberget, a longer-lived public testing environment, to expose applications and infrastructure to Glamsterdam before Sepolia and Hoodi. No Hoodi or mainnet dates are confirmed, although developers have discussed a possible December mainnet activation. Sepolia remains a planning target rather than a guaranteed fork date, pending a stable Devnet-11 and subsequent testnet performance.
