Glamsterdam’s Hoodi launch hits the gas brakes after 13 real-world examples surface

Ethereum core developers postponed the Glamsterdam upgrade on the Hoodi testnet from October 26, 2026 after ChainSecurity identified gas-accounting changes that could affect existing mainnet smart contracts. The decision was made during All Core Devs Execution (ACDE) call #248. No replacement Hoodi date has been set, and a new schedule will be announced separately. The postponement requires no action on mainnet or from $ETH holders, while the Q4 2026 mainnet window remains open, with December as a candidate.

The delay removes the Amsterdam execution-layer activation, the Gloas consensus-layer activation and the planned increase of Hoodi’s gas limit to 200 million from the October 26 epoch. Ethereum developers had been considering early December for the mainnet deployment, with plans to finalize its schedule after successful Hoodi testing. Node operators will need to update their clients for the rescheduled activation.

ChainSecurity warned on Oct. 13 that EIP-8037 and EIP-8038 could weaken safeguards against insufficient gas griefing. Under the proposed rules, gas could be returned to a contract after an operation fails, allowing it to continue when it previously would have stopped and potentially interfering with security checks that rely on the gas remaining during a transaction. In an attack known as insufficient gas griefing, a malicious caller deliberately provides too little gas for a legitimate smart contract operation to succeed, the researchers said.

ChainSecurity said the changes could allow contracts to permanently record failed operations; an affected contract could remove a user’s claim or disable the option to retry it, leaving the user unable to complete an otherwise valid operation. It cautioned that Glamsterdam would not make every gas-related security check unreliable: some safeguards could still work, but developers would need to review them against the new gas rules. In an Oct. 21 comment on GitHub, pseudonymous security researcher pcaversaccio described the risks as “serious” and called for a reassessment of the hard fork.

On Friday, ChainSecurity said it had identified “13 real-world examples” and was coordinating responsible disclosure with affected projects, without disclosing details of the examples or identifying the projects. The firm advised developers to check their contracts as soon as possible. The findings followed an Ethereum Foundation (EF) warning that Glamsterdam’s gas model could break wallets, indexers and gas estimators that rely on fixed assumptions. Glamsterdam had already activated on Sepolia on Oct. 6, ahead of the postponed Hoodi deployment.