Ethereum developers have penciled in Oct. 6, 2026, at 13:53 UTC for the Glamsterdam upgrade's activation on the Sepolia testnet, but the date stays conditional until a private devnet run proves stable. Devnet-11, launching Sept. 14, has replaced Devnet-10 as the next test developers are watching after earlier trials exposed consensus and execution bugs.
Sepolia date hinges on a devnet that hasn't run clean yet
Ethereum developers tentatively agreed on Sepolia epoch 351232 for Glamsterdam's activation, corresponding to Oct. 6 at 13:53 UTC, during the Sept. 3 All Core Developers Consensus meeting. That decision came before developers had demonstrated stable performance across the private testnet networks built for Glamsterdam, so the date functions as a planning target rather than a lock.
Protocol researcher Christine D. Kim reported on Sept. 10 that the caveats around the Oct. 6 date still hold. She said on Sept. 11 that attention has shifted to Glamsterdam-Devnet-11, expected to launch Monday, Sept. 14, after earlier plans had pointed to Devnet-10 as the next major test.
Consensus and EIP-8037 bugs pushed the timeline back
Earlier trials surfaced faults on both layers of the protocol. Ethereum Foundation developer operations engineer Stefan Starflinger said Devnet-8 revealed a consensus-layer problem tied to blocks that repeated a parent hash. According to crypto.news: "You could get the whole network to stop". Devnet-9 then suffered non-finality, prompting engineers to dig into more edge cases across a roughly 1,000-validator test network, the largest Glamsterdam devnet by validator count at that stage.
Separately, Ethereum Foundation researcher Maria Silva flagged an implementation issue tied to EIP-8037, the proposal that separates state-creation gas costs from normal execution costs. The fault required execution clients to revise their code, and the proposal remains under peer review.
Hoodi and mainnet dates stay unset
Developers have declined to fix a date for the Hoodi testnet while Sepolia remains conditional. Teku developer Enrico del Fante backed waiting, citing the Devnet-9 problems and favoring more testing time after the Sepolia call. A December mainnet activation remains a possible target, but no epoch, timestamp, or client release schedule has been published.
The immediate checkpoint is Devnet-11's Sept. 14 launch, when client teams will examine finality and cross-client behavior before deciding whether the Oct. 6 Sepolia date holds.
Source: crypto.news
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