A new feature shipped in Sui's v1.72 release exposed an edge case in the Layer-1 blockchain's gas-charging logic that halted mainnet three separate times across May 28 and May 29, with each fix either triggering or exposing the next failure, the Sui Foundation said in a post-mortem published Sunday.
The first outage began at roughly 7 a.m. PT on Thursday and lasted close to seven hours.
According to the foundation, it stemmed from a rare issue in how the network charged gas for transactions paying with a mix of the new address-balance feature and traditional coin objects. The bug caused validators to crash with an underflow error when a transaction was canceled for insufficient funds, but the gas-smashing routine still tried to spend those same funds.
Think of a coin object as a digital banknote. A user's SUI balance isn't a single number — it's a stack of distinct "notes," each with its own ID, that can be moved or combined. The wallet might hold three coin objects worth 60, 30, and 10 SUI rather than a single 100-SUI balance. To pay for something, the network combines the notes it needs.
Validators are computers (and the operators behind them) that run the network by processing transactions, voting on which ones are valid, and keeping the chain alive.
