Ethereum core developers have delayed the Glamsterdam fork on the Hoodi testnet following a ChainSecurity report that identified compatibility risks in EIP-8037 and EIP-8038. The proposed gas pricing changes interact with certain contract patterns in ways that could cause unexpected behavior, prompting developers to pause the rollout and conduct further review.
The Compatibility Issue
The delay stems from a fundamental problem with how the proposed changes handle gas refunds during transactions. According to Ethereum researcher Toni Wahrstätter, gas already spent can be returned mid-transaction, causing the gasleft() value to increase during execution. This breaks an invariant that many contracts rely on—the assumption that gas usage only moves downward.
ChainSecurity identified 13 real-world cases where this behavior creates problems. Developers had been aware that hardcoded gas values would be affected by repricing, but this new finding reveals a different issue rooted in contracts that depend on consistent downward gas movement.
Consequences for Contracts
The broken invariant creates two main failure modes. In one scenario, a before-and-after gas counter underflows, causing the transaction to revert. In another, a failed sub-call returns gas, allowing an unreachable code path to execute and making the transaction appear successful when it should have failed.
A related problem affects gas measurement itself. Contracts and tools that compare gas values before and after a call may undercount usage because the state gas reservoir is not visible during execution. This could lead to inaccurate gas reporting.
Next Steps
Developers spent the weekend assessing the scope of the issue and now plan to examine affected contracts closely this week. The path forward depends on the findings. Resolution might require coordination among dapp developers, auditors, and node operators, or it could require changes to the specification itself.
Wahrstätter called on app developers and auditors to review their contracts for issues with EIP-8037 and EIP-8038 and report any problems they find.
