Ethereum developers have postponed the planned Glamsterdam upgrade on the Hoodi test network after researchers identified potential risks involving how existing smart contracts handle failed operations. The Ethereum Foundation announced the delay on October 22, 2026, removing the previously scheduled October 26 activation while developers investigate how proposed changes to gas accounting could interact with contracts already deployed on the network.
The decision highlights a major challenge in blockchain development: protocol upgrades must improve performance without unexpectedly changing the behavior of applications that depend on existing execution rules. Although the issue has not been confirmed as an active exploit affecting Ethereum mainnet, the findings have prompted developers to conduct further compatibility and security reviews before rescheduling the test.
Why Ethereum postponed the Glamsterdam upgrade
The concern centers on Ethereum Improvement Proposals EIP-8037 and EIP-8038, which affect gas accounting and the costs associated with contract execution and database growth. Gas is the unit Ethereum uses to measure computational work and certain operations. Smart contracts rely on predictable execution behavior, including what happens when a transaction runs out of gas or a called contract fails.
Security researchers at ChainSecurity reported that the proposed changes could alter how some contracts behave when an operation fails. In particular, a contract designed to catch an error and continue with another step might have a different amount of gas available under the new rules. Depending on its design, that could change whether the failure-handling logic completes or the entire transaction reverts.
The reverse problem is also possible: some operations that previously completed within an expected gas budget could require more gas under the proposed accounting rules. That could cause certain transactions to fail even when the application was designed around the earlier cost assumptions. These are compatibility concerns that need to be assessed against real contract logic, not proof that every existing contract is vulnerable.
What the findings mean for existing smart contracts
Smart contracts often depend on carefully structured error handling. Developers may intentionally rely on a failed internal operation causing a complete transaction rollback, preventing a partial state change from being recorded. If a protocol upgrade changes the amount of gas remaining after an operation is undone, some of those assumptions may no longer hold as expected.
ChainSecurity's analysis described mechanisms through which the proposed changes could affect contract execution. CoinDesk reported that the researchers had demonstrated the potential behavior, but had not publicly established that a major production protocol was exploitable as a result. Ethereum's testnet delay should therefore be understood as a precautionary engineering decision rather than evidence that user funds are currently being stolen through this issue.
For developers, the episode reinforces the importance of testing contracts against upcoming protocol changes. Applications that depend on low-level gas behavior, complex error handling, or interactions between multiple contracts may need particular attention during upgrade testing. Security reviews should examine not only whether code compiles and passes ordinary tests, but also whether its assumptions remain valid under the new execution rules.
Glamsterdam's broader network goals remain important
The Glamsterdam upgrade is part of Ethereum's continuing effort to improve the network's capacity and execution architecture. Its planned changes include enshrined proposer-builder separation and block-level access lists, alongside adjustments to gas pricing intended to better reflect the costs of execution and state growth.
The upgrade had already activated on the Sepolia testnet on October 6. Hoodi was scheduled to provide another public testing stage, including a planned increase in its gas limit to 200 million. The postponement removes that scheduled activation and the associated gas-limit change until developers establish a revised plan.
The Ethereum Foundation has not announced a replacement Hoodi activation date. It has also clarified that the postponement concerns the test network and does not set a mainnet activation date. Ethereum mainnet users and ETH holders do not need to take action solely because of this announcement.
What developers and users should watch next
The next important milestone is a revised testing schedule accompanied by clear guidance for node operators, validators, and application developers. Operators running Hoodi infrastructure should follow the Ethereum Foundation's latest instructions and check that their execution and consensus clients reflect the postponed activation rather than the superseded October 26 schedule.
Smart contract teams should monitor the EIP discussions and relevant security analyses, then test applications against updated specifications and client implementations before any future activation. The extent of any required changes will depend on each application's code and its reliance on the affected gas-accounting behavior.
The delay demonstrates why major blockchain upgrades require more than performance benchmarks. Ethereum must also preserve predictable contract execution across a large ecosystem of applications that may have been written years before a proposed change. A careful postponement can give developers time to investigate unexpected interactions before they reach a live network.
For the wider blockchain industry, the episode is a reminder that protocol-level improvements and smart contract compatibility are closely connected. The outcome of the Glamsterdam review will matter not only for Ethereum's upgrade schedule, but also for how developers evaluate the safety of future changes to widely used blockchain infrastructure.
