Ethereum’s next major upgrade just hit a speed bump. Core developers postponed the Glamsterdam upgrade on the Hoodi test network, which had been scheduled for October 26, 2026, at 17:42:48 UTC, after security researchers showed that proposed gas-accounting changes could alter how existing smart contracts handle failures. No new date has been set. Nothing changes for people who simply hold ETH, but the delay is a useful look at how Ethereum handles risk.
What happened
The Ethereum Foundation announced on October 22 that Glamsterdam on Hoodi, previously set for October 26 at 17:42:48 UTC, has been postponed. Per the post:
- Core developers made the call on All Core Devs Execution call #248 “to allow for further investigation of interactions of EIP-8037 with mainnet smart contracts.”
- The delay also removes a planned increase of Hoodi’s gas limit to 200 million.
- There is no replacement activation date. A new schedule “will be announced at a later date.”
- The Foundation says “no action is required from Ethereum mainnet users or ETH holders as a result of this update.”
CoinDesk reported that Glamsterdam completed its Sepolia testnet activation on October 6, making Hoodi the next public rehearsal. Ethereum mainnet has no confirmed Glamsterdam date.
The problem researchers found
The concern traces to an October 13 analysis by security firm ChainSecurity. It looked at two proposals bundled into Glamsterdam:
- EIP-8037 changes how Ethereum charges for creating new state (data stored on-chain) and adds a separate “state-gas reservoir.”
- EIP-8038 reprices state access.
Here is the simplified version. Many smart contracts call other contracts and need to handle the case where that call fails. A known attack, called insufficient gas griefing, involves deliberately sending too little gas so an otherwise valid operation fails, while leaving just enough for the contract to record a permanent failure. Developers defend against this partly by assuming that after a failed call, there will not be enough gas left to finish certain actions, so the whole transaction reverts.
ChainSecurity showed that Glamsterdam’s new rules can break that assumption in both directions:
- More gas than expected. The reservoir and new refill mechanics can restore gas after a failure, letting a failure handler finish when it previously would have reverted.
- Less gas than expected. Creating a new storage slot could cost 110,020 execution gas (12,100 + 97,920) when the state-creation charge falls on execution gas, versus 22,100 under the current Osaka rules, according to ChainSecurity. Hard-coded gas budgets that were safe under the old rules might now be too small.
CoinDesk notes ChainSecurity demonstrated the mechanisms but has not publicly shown that a major production protocol is exploitable, and that the findings do not indicate any contracts were being exploited as of its Oct. 23, 2026, report. Which specific contracts could be affected is not public: TBD.
Why it matters
This is the process working. Testnets exist to surface problems before real money is at stake. Developers pausing a rehearsal to study an issue raised by outside auditors is the system doing its job. It is a better outcome than discovering the issue after a mainnet launch.
Upgrades that change gas rules are high-stakes. Ethereum hosts a huge number of contracts written years ago, under assumptions about how gas works. Changing those rules, even for good reasons like controlling the growth of on-chain data, can create subtle behavior changes in code that nobody is actively maintaining. The delay underlines how hard it is to upgrade a platform where old code cannot simply be rewritten.
Expect knock-on delays. Glamsterdam’s mainnet timing was already unconfirmed. Any changes to EIP-8037, or extra auditing, could push the full upgrade further out. The new timeline is TBD.
Developers have homework. ChainSecurity’s guidance for teams is to revisit failure-handling code, re-check fixed gas budgets under the new pricing, and where possible propagate failures so the whole operation reverts. Projects with contracts that catch failed calls should review them now rather than waiting for a new date.
What to watch
- The next All Core Devs calls for a revised Hoodi schedule.
- Whether EIP-8037 is modified, delayed or kept as is.
- Any updated guidance from client teams for node and validator operators.
The bottom line
Glamsterdam’s Hoodi test is on hold because researchers found that new gas rules could change how existing contracts behave when things go wrong. ETH holders do not need to do anything. Smart contract developers should check their failure-handling logic, and everyone should expect Glamsterdam’s timeline to stay fluid until developers sign off.
Sources
- Ethereum Foundation Blog, “Glamsterdam on Hoodi Postponed” (Oct. 22, 2026): https://blog.ethereum.org/2026/10/22/glamsterdam-hoodi-delay
- Ethereum Foundation Blog, “Glamsterdam Hoodi Testnet Announcement” (Oct. 16, 2026): https://blog.ethereum.org/2026/10/16/glamsterdam-hoodi-announcement
- ChainSecurity, “Glamsterdam Hard Fork: When Spent Gas Comes Back” (Oct. 13, 2026): https://www.chainsecurity.com/blog/glamsterdam-gas/
- CoinDesk, “Ethereum delays Glamsterdam test after security devs flag risk to existing contracts” (Oct. 23, 2026): https://www.coindesk.com/tech/2026/10/23/ethereum-delays-glamsterdam-test-after-security-devs-flag-risk-to-existing-contracts