Ethereum targets Oct. 6 for Glamsterdam on Sepolia

Ethereum developers have set a provisional activation time for the Glamsterdam upgrade on the Sepolia testnet at 13:53 UTC on 6 October 2026. The schedule remains conditional pending the outcome of a forthcoming private devnet trial.

Current testing roadmap

The next private test, labeled Devnet‑11, is slated to launch on 14 September. This follows earlier plans for Devnet‑10, which were superseded after bugs were uncovered in prior trials. Devnet‑11 will focus on confirming fixes for consensus‑layer and execution‑client issues identified in earlier runs.

Issues uncovered in earlier devnets

• Devnet‑8 exposed a consensus problem where blocks could repeat a parent hash, potentially halting the network.
• Devnet‑9 experienced non‑finality, prompting deeper investigation of validator behavior.
• An execution‑client bug related to EIP‑8037, which changes gas accounting for state creation, required specification revisions.

Implications for public testnets and mainnet

Sepolia’s activation epoch (351232) provides a planning reference for client teams, infrastructure operators, and dApp developers, but it is not a final commitment. If Devnet‑11 reveals a major fault, the Oct. 6 date could be postponed during an All Core Developers meeting.

The subsequent public testnet, Hoodi, has no confirmed activation date. Developers have emphasized the need for a stable Sepolia fork before fixing Hoodi’s schedule. A potential mainnet rollout in December has been discussed, but no epoch or timestamp has been published.

Next steps

Stakeholder groups such as Lido and Optimism have requested at least one stable day on Sepolia before the fork proceeds. Client diversity—multiple independent execution and consensus clients—adds complexity, as faults in any single client can affect the overall test outcome.

The immediate milestone is the Devnet‑11 launch on 14 September, after which the community will assess finality, cross‑client interoperability, and the effectiveness of recent bug fixes to determine whether the Oct. 6 Sepolia activation remains viable.