Ethereum core developers have indefinitely postponed the Glamsterdam upgrade's October 26, 2026 rehearsal on the Hoodi testnet. The decision followed disclosures from security firm ChainSecurity identifying vulnerabilities in EIP-8037 and EIP-8038 that affect 13 deployed mainnet smart contracts. The gas-accounting flaws allow failed transactions to complete permanently instead of cleanly reverting, threatening funds in automated protocols. The Hoodi delay leaves target mainnet dates in December 2026 unconfirmed.
Postponement of the Hoodi upgrade
- ▪The postponement of the Glamsterdam upgrade was agreed upon during the October 22, 2026, All Core Developers Execution meeting #248.
- ▪Ethereum developers postponed the Glamsterdam upgrade on the Hoodi testnet after security researchers identified gas-accounting risks affecting smart contracts.
- ▪The Ethereum Foundation announced on October 22, 2026, that the Glamsterdam upgrade scheduled for October 26, 2026, on Hoodi would no longer proceed.
Hoodi testnet postponement impact
- ▪The Hoodi testnet postponement also suspends the planned activations of both the Amsterdam execution layer and the Gloas consensus layer on the network.
- ▪The Hoodi testnet postponement cancels the planned increase in Hoodi's gas limit to 200 million.
Client updates to unschedule activation
- ▪Lodestar released consensus client v1.50.1 and Besu released execution client 26.10.1 on October 22, 2026, to unschedule Glamsterdam on Hoodi.
- ▪The Ethereum Foundation instructed Hoodi node operators and validators to update execution and consensus client software to remove the October 26, 2026, activation.
Mainnet deployment timeline uncertainty
- ▪The Ethereum Foundation has not announced a replacement activation date for Hoodi or confirmed a mainnet deployment schedule for Glamsterdam.
- ▪Prior to the Hoodi postponement, Ethereum developers were considering December 1, December 8, and December 9, 2026, as potential mainnet activation dates.
Sepolia testnet status
- ▪The Glamsterdam upgrade successfully activated on the Sepolia testnet on October 6, 2026, running with a gas limit of approximately 200 million.
- ▪Following the Hoodi testnet postponement, Sepolia is the only remaining active testnet where the Glamsterdam upgrade is currently running.
ChainSecurity security findings and disclosure
- ▪ChainSecurity disclosed on October 22, 2026, that it had identified 13 real-world deployed mainnet contracts vulnerable to gas-accounting changes under Glamsterdam.
- ▪ChainSecurity stated it is conducting responsible disclosure with the 13 affected projects while declining to publicly identify specific contracts.
- ▪Blockchain security firm ChainSecurity published an analysis on October 13, 2026, warning that EIP-8037 and EIP-8038 could undermine smart contract failure safeguards.
EIP-8037 state-gas mechanics
- ▪EIP-8037's state-gas reservoir passes to child calls without being subject to the EIP-150 rule that caps forwarded execution gas at 63/64.
- ▪Under EIP-8037, gas restored during execution allows contracts designed around older rules to complete failure-handling instructions instead of cleanly reverting.
- ▪EIP-8037 introduces a state-gas reservoir, creating a separate gas budget specifically for state-creation costs that operates independently of standard execution gas.
EIP-8038 protocol proposal
- ▪EIP-8038 modifies the gas costs associated with accessing and modifying existing blockchain state.
- ▪EIP-8038 aims to increase Ethereum's transaction capacity by aligning gas charges more closely with the resources smart contracts consume.
Storage slot gas pricing
- ▪ChainSecurity calculated that creating a new storage slot under proposed Glamsterdam rules could require up to 110,020 gas when state allowance is exhausted.
- ▪Under Ethereum's current execution model, writing a value to a brand-new storage slot costs 22,100 gas from a single shared pool.
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