Ethereum developers have tentatively scheduled the Glamsterdam upgrade for activation on Sepolia at 13:53 UTC on October 6, 2026, according to reports from ACDC #186 meeting notes and subsequent reporting from Ethereum protocol researcher Christine D. Kim. The date replaces an earlier September 28 target discussed by core developers, providing the clearest public-testing milestone yet for the network's next major upgrade. However, October 6 remains tentative and depends on developers achieving a stable Glamsterdam devnet transition beforehand. During the September 3 All Core Developers Consensus meeting, participants agreed on Sepolia epoch 351232 for the proposed activation, which corresponds to the October 6 timeframe. Developers are treating October 6 as a target rather than a guaranteed fork date, with the additional testing reflecting the complexity of Glamsterdam's headline consensus change.
The testing plan has advanced to Devnet-11, expected to launch on Monday, September 14, replacing earlier expectations centered on Devnet-10 testing plans, as reported by Kim on September 11. Earlier Glamsterdam trials exposed consensus and execution bugs, including a consensus-layer problem involving blocks that repeated a parent hash during Devnet-8 testing, which could cause the entire network to stop. On the execution side, Ethereum Foundation researcher Maria Silva reported an implementation problem involving EIP-8037, requiring execution clients to revise their implementations and leading to specification work. The Ethereum Foundation has already launched Platåberget, a longer-lived public testing environment specifically designed to expose applications and infrastructure to Glamsterdam before the upgrade reaches Sepolia and Hoodi. Earlier testing exposed issues including a builder-deposit caching bug that caused non-finality during a Glamsterdam devnet transition, with affected client teams subsequently developing fixes, but developers want another clean transition before advancing to Sepolia.
Ethereum developers have set a target deadline of December 2029 for implementing quantum-resistant cryptography at the base protocol level, anticipating a potential 'Q-day' in 2030 when quantum computers could crack existing cryptographic security. This timeline comes as the U.S. Department of Commerce approved $300 million in CHIPS Act grants to quantum computing companies Rigetti, D-Wave, and Quantinuum, with each company receiving up to $100 million in funding. Recent analysis suggests that breaking 256-bit elliptic curve cryptography might require fewer than 1,200 error-corrected qubits, prompting proactive measures by blockchain developers. The transition poses unique challenges for Ethereum, which faces a complex coordination challenge in migrating wallets and applications after the core protocol upgrade. While Bitcoin lacks a formal deadline, significant work is underway on proposals (BIP-360 and BIP-361) for new post-quantum transaction formats and a transition away from current ECDSA and Schnorr signatures.
Developers have declined to schedule Glamsterdam on Hoodi while Sepolia remains conditional, with Hoodi expected to serve as the second public testnet stage. Teku developer Enrico del Fante supported waiting before fixing the Hoodi date, citing recent Devnet-9 problems and favoring allowing more testing time after the Sepolia decision. Ethereum's official roadmap currently targets Glamsterdam for mainnet during the fourth quarter of 2026 but does not provide a specific date. That uncertainty is deliberate: developers intend to complete Sepolia and Hoodi testing before committing to mainnet activation. A successful October 6 Sepolia fork would represent an important milestone, but not the final hurdle, as developers can then assess client compatibility, network finality and downstream infrastructure before choosing mainnet activation. The schedule also matters because Ethereum developers are simultaneously preparing Hegotá, the upgrade expected after Glamsterdam in 2027, which is currently expected to include fork-choice enforced inclusion lists and Frame Transactions.
Glamsterdam introduces two major headline features that fundamentally change Ethereum's infrastructure. The proposer-builder separation (ePBS) brings the relationship between validators and block builders directly into Ethereum's protocol, moving that relationship into consensus itself and separating agreement over a block from its processing while reducing reliance on trusted third-party software. This substantially changes Ethereum's block-production pipeline. The upgrade also includes Block-Level Access Lists (BALs) that identify which parts of Ethereum's state a block accesses and modifies, allowing clients to understand dependencies before executing transactions and laying groundwork for parallel execution. The architecture potentially allows Ethereum to process substantially more activity without forcing node hardware requirements upward at the same rate. Glamsterdam includes a coordinated package of gas repricings aimed at supporting roughly a 200 million gas floor, with the Ethereum Foundation warning that wallets, indexers and gas-estimation tools relying on hardcoded assumptions about Ethereum's maximum gas limit will need to update. Other changes increase the maximum deployed contract size from 24 KiB to 64 KiB and maximum initcode from 48 KiB to 128 KiB.
