Ethereum Postpones Glamsterdam Upgrade on Hoodi After Gas-Accounting Concerns

Ethereum developers have delayed the Glamsterdam upgrade scheduled for the Hoodi test network after researchers flagged a gas-accounting interaction that could change how smart contracts behave when operations fail. The pause was announced during the All Core Devs Execution meeting to allow further review of how proposed changes might affect contracts already deployed on mainnet.

The upgrade had been set to activate on Oct. 26 at 17:42:48 UTC but was pulled back for investigation. No new activation date has been set for Hoodi, and Ethereum’s mainnet timetable remains undecided while developers analyze the reported issues.

What triggered the delay

Security firm ChainSecurity published an analysis on Oct. 13 showing that combining EIP-8037 with EIP-8038 could produce unexpected results for contracts when a called contract runs out of gas or when transaction fees are exhausted. The core of the concern is a proposed change to how the protocol charges for creating new state records — a mechanism intended to control the growth of Ethereum’s on-chain database as throughput increases.

Under the new proposal, gas refunds for certain state creations can be restored if those changes are later reverted. That adjustment can leave a caller contract with enough remaining gas to complete a failure-handling routine that would previously have been unable to finish and therefore caused the entire transaction to revert.

Potential behavioral shifts in existing contracts

Some smart contracts intentionally rely on insufficient remaining gas to force a revert when a nested call fails. For example, a contract might attempt an action, and if that action fails it expects the overall transaction to undo any partial changes. The proposed accounting changes could permit the failure-handler to run far enough to record or change state, producing an outcome different from what contract authors originally expected.

ChainSecurity also calculated scenarios where gas costs increase instead of decrease. In one situation, creating a new storage slot could consume 110,020 gas when a separate allowance has been depleted, versus 22,100 gas under the current rules. That escalation could make otherwise valid operations run out of gas and fail.

Scope and evidence

The findings focus on how deployed software would behave under the proposed rules. ChainSecurity has demonstrated the mechanics behind the issue but has not shown that a major live protocol has been exploited as a result. There is no evidence of ongoing exploitation on mainnet.

What Glamsterdam includes and next steps

Glamsterdam includes multiple changes besides the gas-accounting adjustments: a revised block-builder selection system and enhancements aimed at supporting larger blocks. The upgrade completed its Sepolia testnet activation on Oct. 6, and Hoodi was intended to be the next public rehearsal alongside a planned gas limit increase to 200 million — both of which are now postponed.

Developers will continue investigating the interactions between EIP-8037 and related proposals. Until the community reaches greater confidence that existing contracts will not be unpredictably altered, the team has not set a replacement activation date for Hoodi or mainnet.