Ethereum's core developers have postponed a test run of Glamsterdam, the network's next major upgrade, which would raise some transaction fees, after auditors warned the change could put some contracts holding user funds at risk. The test was set for Hoodi, one of Ethereum's test networks. The Oct. 26 activation, scheduled for 17:42:48 UTC (1:42 p.m. ET), is called off, and "a new activation date has not been set," the Ethereum Foundation said on Thursday [1]. For companies building on Ethereum, the fee repricing stays on hold while developers check which contracts could break.
Hoodi is a public test network where client software and apps rehearse an upgrade before it reaches the main network. The upgrade has already run on Sepolia, another Ethereum test network, where it activated on Oct. 6, according to the Foundation [6]. The developers decided the delay on Thursday's All Core Devs execution call, number 248. The Foundation said the aim is "to allow for further investigation of interactions of EIP-8037 with mainnet smart contracts" [1].
What the change does
EIP-8037 is one of the proposals bundled into Glamsterdam. It raises the gas cost of creating new state, meaning the new accounts, storage entries and contracts every Ethereum node must store permanently. Gas is the unit Ethereum uses to price computation and storage; users pay fees in proportion to it. The proposal's stated goal is "avoiding excessive state growth under increased block gas limits" [4]. The block gas limit is the cap on how much work fits in one block, so a higher limit means more transactions per block.
The proposal's authors estimate how much more creating new state would cost in gas [4]:
- A new account goes from 25,000 to 183,600 gas, about 7 times as much.
- A new storage slot goes from 20,000 to 97,920 gas, about 5 times.
- Deploying a 24-kilobyte contract goes from about 4.9 million to 37.8 million gas, about 8 times.
These are design figures from the proposal, not fee forecasts. The authors write that "users and dApp developers will experience an increase in transaction costs associated with creating a new state" [4]. The trade-off, in their framing, is room to scale. They extrapolate that at a 200 million gas limit, state would grow about 387 GiB a year without the change [4].
The postponement also pulls a second change from the Hoodi schedule. It "removes the gas-limit schedule that would have raised Hoodi's gas limit to 200M at the same epoch," the Foundation said [1].
Why developers paused
The concern came from auditors. On Oct. 21, the day before the call, developer pcaversaccio posted on the call agenda that ChainSecurity had found "serious security risks" from EIP-8037 and its companion EIP-8038. The risks affect applications, and he said disclosure to affected protocols was under way. "The fundamental 'broken' thing is that gasleft() can increase," he wrote [2]. gasleft() is the function a smart contract calls to check how much gas it has left.
ChainSecurity's Oct. 13 write-up explains the mechanism. Contracts often assume a failed call has used up the gas it was given, and some rely on that to stop an attacker from forcing a failure on purpose. Under Glamsterdam, the firm wrote, "a failure path that previously reverted can now complete," even with unchanged contract code [5]. The EIP's own text concedes part of this: contracts that measure gas use as the difference between two readings "can get a negative result," and "contracts already deployed with such metering cannot be fixed" [4].
On the call, Hubert of ChainSecurity said the firm had "found 13 major DeFi projects that are affected by this," then added: "not all of them are major DeFi projects" [7, at 00:22:55 and 00:23:08]. DeFi, or decentralized finance, covers lending and trading apps that run on smart contracts. He said covering the big projects would take "at least 2-3 weeks" [7, at 00:42:32]. Among the projects found, "many of them are upgradable," he said, and others "might be able to migrate" [7, at 00:43:26 and 00:43:32].
The objection
Developers did not reject EIP-8037. An automated meeting summary posted to the Ethereum Magicians forum attributes the problems to "incorrect developer assumptions about gas behavior rather than inherent security flaws" [3]. That summary contains errors, including a wrong proposal number for the fork, so it is cited only for what it reports was said. It also records that participants weighed three responses for the main network: addressing the issues before a mainnet rollout, delaying mainnet with the current specification, or changing the Glamsterdam specification [3]. No option was chosen. The EIP page still lists the proposal in "Last Call" review, with a deadline of Nov. 1, 2026 [4].
Fig. 1. Glamsterdam's Hoodi date is gone, with no replacement. The December mainnet dates shown were heads-up-only placeholders on the call agenda, never adopted; no mainnet date is set [1][2].
What to watch
The Foundation told Hoodi node and validator operators to install client releases whose notes confirm the Oct. 26 activation is removed. It said it would list those releases as they ship [1]. The post "does not set a Glamsterdam mainnet activation date, and no action is required from Ethereum mainnet users or ETH holders," it said [1].
The next signals are a revised Hoodi schedule, which the Foundation said "will be announced separately," and any change to EIP-8037's text [1][4]. Until either appears, there is no date for the fee changes on any network.
Sources
- Ethereum Foundation Protocol Cluster, "Glamsterdam on Hoodi Postponed," Oct. 22, 2026, https://blog.ethereum.org/2026/10/22/glamsterdam-hoodi-delay, accessed Oct. 22, 2026, 5:14 p.m. ET.
- ethereum/pm, "All Core Devs - Execution (ACDE) #248, October 22, 2026," issue #2267 and comments (pcaversaccio, Oct. 21, 2026), https://github.com/ethereum/pm/issues/2267, accessed Oct. 22, 2026, 5:14 p.m. ET.
- Ethereum Magicians, "All Core Devs - Execution (ACDE) #248," automated meeting summary posted Oct. 22, 2026, https://ethereum-magicians.org/t/29937, accessed Oct. 22, 2026, 5:14 p.m. ET.
- Maria Silva et al., "EIP-8037: State Creation Gas Cost Increase," Ethereum Improvement Proposals (Last Call), https://eips.ethereum.org/EIPS/eip-8037, accessed Oct. 22, 2026, 5:14 p.m. ET.
- ChainSecurity, "Glamsterdam Hard Fork: When Spent Gas Comes Back," Oct. 13, 2026, https://www.chainsecurity.com/blog/glamsterdam-gas, accessed Oct. 22, 2026, 5:14 p.m. ET.
- Ethereum Foundation Protocol Cluster, "Glamsterdam Hoodi Testnet Announcement," Oct. 16, 2026 (with Oct. 22 update note), https://blog.ethereum.org/2026/10/16/glamsterdam-hoodi-announcement, accessed Oct. 22, 2026, 5:14 p.m. ET.
- ethereum/pm, ACDbot artifacts for ACDE #248, Oct. 22, 2026, corrected call transcript (timestamps 00:22:55, 00:23:08, 00:42:32, 00:43:26, 00:43:32), https://github.com/ethereum/pm/blob/master/.github/ACDbot/artifacts/acde/2026-10-22_248/transcript_corrected.vtt, accessed Oct. 22, 2026, 5:18 p.m. ET.
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