Ethereum Developers Warn of Contract Risks in Glamsterdam Upgrade

Why Gas Repricing Matters for Contract Stability

On August 24, 2026, Ethereum core developers issued a warning that the upcoming Glamsterdam upgrade could disrupt a small number of Layer 1 smart contracts due to changes in gas pricing mechanics. The alert was shared during a developer call focused on the network’s next major hard fork, scheduled for later this year. The concern centers on EIP-80, a proposal that adjusts gas costs for certain operations to improve efficiency and security. While the change aims to optimize resource usage, developers noted that some existing contracts relying on current gas assumptions might behave unexpectedly or fail after the upgrade. The affected contracts are described as a niche group, primarily those with hardcoded gas limits or specific dependencies on opcodes being repriced.

The Glamsterdam upgrade includes EIP-80, which modifies the gas cost of specific Ethereum Virtual Machine (EVM) operations to better reflect their actual computational load. Developers explained that while most contracts will remain unaffected, those that have baked in fixed gas expectations—such as certain multisig wallets, escrow systems, or legacy DeFi protocols—could run out of gas during execution if their limits are not adjusted. One developer noted during the call that „even a small shift in gas pricing can break assumptions baked into code years ago.” The Ethereum Foundation emphasized that the risk is limited and that affected projects have been identified through static analysis tools. Teams behind these contracts are being contacted directly to update their code before the upgrade activates on mainnet.

Could This Affect User Funds or Network Security?

Developers stressed that the risk does not compromise Ethereum’s core security or lead to fund loss for users interacting with standard applications. Instead, the issue primarily affects contract functionality—such as a transaction failing to complete rather than being exploited. However, they warned that failed transactions could still result in wasted gas fees for users attempting to interact with vulnerable contracts. To mitigate this, the Ethereum Cat Herders team is preparing a public list of flagged contracts so users and auditors can verify compatibility. The upgrade will proceed as planned, with developers urging contract owners to test their code on Glamsterdam testnets and adjust gas limits where necessary. No delays to the upgrade timeline have been proposed.

Which contracts are most at risk from the Glamsterdam gas changes? Contracts with hardcoded gas limits or dependencies on specific EVM opcodes being adjusted in EIP-80 are most vulnerable, particularly older or minimally maintained protocols.

Frequently Asked Questions

Will user funds be lost if a contract breaks during the upgrade? No, the issue relates to contract functionality failure, not security flaws; funds remain safe but transactions may fail and consume gas.

How can developers check if their contract is affected? Developers should simulate transactions on Glamsterdam testnets and review gas usage, especially for functions interacting with low-level opcodes like SSTORE or CALL.