Ethereum core developers have paused the rollout of the network's next major upgrade, Glamsterdam, on the Hoodi testnet until security concerns tied to eight smart contract invariants are resolved, according to a Friday blog post from the Ethereum Foundation. Hoodi is one of Ethereum's public test networks, where upcoming protocol changes are rehearsed under live conditions before mainnet activation.

At the center of the delay are two Ethereum Improvement Proposals (EIPs) included in the upgrade, EIP-8037 and EIP-8038, which change how gas is charged for certain operations. Gas is the unit used to measure the computational cost of transactions and smart contract execution on Ethereum. According to the Foundation, some existing Ethereum projects depend on the assumption that specific operations will always cost a fixed amount of gas — an assumption that the new gas-pricing rules would invalidate. Because those assumptions sit in already-deployed code, the repricing is being treated as a security concern for the upgrade rather than a routine cost adjustment.

The decision followed an Oct. 13 report from smart contract auditing firm ChainSecurity, which found that the two proposals could break contracts that rely on fixed gas-related assumptions when external calls fail. Developers are now investigating concerns linked to eight smart contract invariants — conditions that deployed contracts expect to hold true as the network operates.

By postponing the Hoodi fork, developers gain additional time to identify potential smart contract issues and determine whether code changes are required before Glamsterdam advances toward mainnet deployment. The Foundation's post stressed that the Hoodi fork will not proceed until the outstanding issues are resolved. The timing of the Hoodi fork now hinges on the outcome of that invariant review, which sits between the upgrade and any mainnet deployment. For readers following the rollout, the markers to watch are whether developers clear the eight invariant concerns and when the Foundation signals that the Hoodi fork can proceed — steps that come before any mainnet move.

The Glamsterdam upgrade went live on the Sepolia testnet on Oct. 6, in one of its final major rehearsals. As the Ethereum Foundation announced in a Sept. 28 blog post, the upgrade is designed to advance Ethereum's layer-1 scaling roadmap through enshrined proposer-builder separation, block-level access lists, and adjustments to gas pricing that better reflect the actual cost of execution.