Ethereum core developers have urgently halted the Glamsterdam upgrade that was originally scheduled to launch on the Hoodi testnet at 17:42:48 UTC on October 26, after discovering potential risks in the smart contract gas billing mechanism.
This decision was made at the all-core developer meeting held on Thursday, aiming to thoroughly assess the impact of the proposed changes on existing contracts on the mainnet. No new upgrade date has been announced yet.
The core of this controversy lies in EIP-8037, a proposal designed to control the expansion of Ethereum's database size by changing how new database records are charged, in order to cope with the continuous growth of network transaction volume.
However, security firm ChainSecurity pointed out in an analysis report on October 13 that EIP-8037, when combined with EIP-8038, could completely change how smart contracts react when gas is exhausted or balances are insufficient.
Many contracts rely on low remaining gas to trigger transaction reversion, but the new rules allow the gas used to create records to be restored upon reversion, which could result in contracts having enough gas to complete faulty processing operations that should have been reverted, thereby causing erroneous states to persist permanently.
Data compiled by Woofun AI shows that this mechanism change brings two-way risks: on one hand, contracts may unexpectedly continue executing; on the other hand, the gas required to create new storage slots surges from 22,100 units to 110,020 units, causing contracts that rely on the original gas budget to also unexpectedly fail when performing valid operations.
Although ChainSecurity demonstrated the relevant mechanism, it did not confirm that any major application protocol could be exploited.
The Glamsterdam upgrade was originally planned to introduce a new system for selecting block builders and enhance the network's ability to handle larger blocks. At the same time, the gas limit on the Hoodi testnet was also planned to increase to 200 million units, but this plan has also been postponed.
The Sepolia testnet version of this upgrade was activated on October 6. Hoodi, as the next public testing environment, has seen its upgrade plan suspended, reflecting developers' cautious attitude toward core protocol changes.
It is worth noting that ChainSecurity's research findings mainly focus on how existing software performs under the proposed rules, and do not indicate that existing smart contracts are actually being exploited due to these proposed changes. However, the potential systemic risk was enough to prompt developers to re-examine the upgrade path.
This delay highlights Ethereum's difficult balancing act between pursuing scalability and maintaining system stability.
As the gas billing mechanism becomes more complex, any subtle change could have far-reaching effects on existing contracts, especially in scenarios involving transaction reversion and state handling.
In the future, developers need to gradually advance network upgrades while ensuring backward compatibility, in order to avoid similar risk events from happening again.
This is a challenge Ethereum must face as it moves toward higher performance, and also an important test of the maturity of its ecosystem.
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