Ethereum’s next upgrade breaks the '21,000 gas' rule wallets rely on

Years of software have been built around that 21,000 as a fixed number. A wallet uses it to decide how much gas to attach to a payment, while a blockchain service uses it to sort transactions. Anything treating it as both the floor and the ceiling for an ETH transfer will reject valid payments or quote fees that come up short.

The reasoning is that the two are not the same amount of work. Paying an account that already exists only adjusts balances Ethereum is tracking anyway, while paying a fresh address adds a record its computers may have to hold forever. Both have carried the same charge until now.

Developers still have time to find the problems. Glamsterdam switches on Thursday on Platåberget, a practice version of Ethereum that uses worthless tokens so developers can break things safely. It reaches two more test networks — Sepolia and Hoodi — after that, and then the real Ethereum.

Nobody sending ETH needs to do anything this week. The warning is aimed at the companies whose software those users depend on.