Ethereum Developers Cancel Oct. 26 Glamsterdam Upgrade on Hoodi

Ethereum developers have postponed the Glamsterdam hard fork on the Hoodi testnet, originally scheduled for October 26, after security firm ChainSecurity identified gas-related risks affecting existing smart contracts. The Ethereum Foundation confirmed the delay to allow investigation into how two proposals, EIP-8037 and EIP-8038, interact with deployed contracts. ChainSecurity said it had found 13 real-world examples of potentially affected contracts and was coordinating responsible disclosure with the projects involved. No new date has been set for Hoodi, and the mainnet timeline, previously discussed as early December, is now uncertain. The upgrade had already activated on Sepolia on October 6. The decision follows warnings that the gas changes could weaken safeguards against insufficient gas griefing attacks.

Background

Glamsterdam is Ethereum's next major upgrade, following the Sepolia activation on October 6, which began producing blocks with a gas limit of nearly 200 million, more than three times mainnet's 60 million. The upgrade introduces block-level access lists for parallel transaction checking and moves the block-building auction into Ethereum's own rules. It also changes how the network charges for creating and accessing stored data through EIP-8037 and EIP-8038, and introduces a separate gas pool for creating new state. Developers had aimed to ship Glamsterdam on mainnet by the end of 2026, ahead of Hegotá, expected in 2027 and potentially adding native privacy features. Hoodi testing was seen as a key step before finalizing a mainnet schedule, with early December under consideration. The Ethereum Foundation had previously warned that Glamsterdam's gas model could break wallets, indexers, and gas estimators relying on fixed assumptions. ChainSecurity's October 13 warning about insufficient gas griefing added to those concerns, prompting a pseudonymous researcher's October 21 GitHub comment calling the risks 'serious' and urging reassessment.

What happened

On October 13, ChainSecurity warned that EIP-8037 and EIP-8038 could weaken safeguards against insufficient gas griefing, an attack where a malicious caller supplies too little gas so a legitimate operation fails. According to ChainSecurity's analysis, under the new rules gas could be returned to a contract after a failed operation, allowing it to continue running when it previously would have stopped. This could interfere with security checks relying on remaining gas and potentially let contracts permanently record failed operations, for example removing a user's claim or disabling retry options. On October 21, pseudonymous security researcher pcaversaccio commented on GitHub that the risks were 'serious' and called for a reassessment of the hard fork. On October 22, ChainSecurity said it had identified '13 real-world examples' and was coordinating responsible disclosure with affected projects, without disclosing details. Decrypt reported that ChainSecurity wrote it had 'just been decided to delay the Glamsterdam hard fork on the Hoodi testnet because of security impacts we identified.' The Ethereum Foundation announced the delay, canceling the October 26 activation. Ethereum researcher Christine Kim said node operators should revert to an older software release without the upgrade scheduled or wait for a new version that cancels it. Preston Van Loon of Prysm said a release removing the upgrade from Hoodi's schedule would follow the same day. No new date has been set.

Market impact

CryptoNews reported that ETH was trading under $2,400 on October 22, losing around 0.5%, and fluctuating between $2,370 and $2,415. The token was approaching the upper end of its daily range, with the $2,400 level in focus. CryptoNews noted that a sustained move above $2,415 could open the door to further upside, while a drop below $2,370 would signal renewed selling pressure. The outlet added that the postponement alone does not establish a bearish outlook for ETH, and that attention will remain on price momentum, market demand, and further updates from Ethereum developers. No other price or flow figures were provided in the sources. The canceled Hoodi activation also removes a planned increase in Hoodi's gas limit to 200 million, which had been scheduled alongside the upgrade. Sepolia, by contrast, had already begun producing blocks with a gas limit of nearly 200 million, more than three times mainnet's 60 million. The sources did not report any other market reactions or trading volumes.

Why it matters

The delay removes a key testing milestone before Glamsterdam's mainnet deployment, leaving the schedule without a confirmed activation date. Developers had discussed potential December activation for mainnet, but those dates should not be treated as confirmed launch targets, according to CryptoNews. The postponement also raises questions about how many deployed contracts are exposed; the Ethereum Foundation is working out how many are affected, Decrypt reported. ChainSecurity urged projects to check their contracts as soon as possible, warning that even with unchanged contract code, a failure path that previously reverted can now complete. The findings follow an earlier Ethereum Foundation warning that Glamsterdam's gas model could break wallets, indexers, and gas estimators relying on fixed assumptions. For traders, CryptoNews said the uncertainty creates a new development milestone to follow rather than a confirmed change to mainnet operations. A prolonged delay could keep attention on the upgrade's readiness, while a revised testing schedule would provide a clearer timeline. The sources did not specify how long the delay might last or what changes, if any, would be required before the next activation.