Sui attributes three mainnet halts to v1.72 bugs

The Sui Foundation published a postmortem saying two distinct bugs in its v1.72 upgrade caused three network halts between Thursday and Friday, taking the Layer 1 blockchain offline while validators restored service.

The foundation’s timeline places the first halt at about 10:00 a.m. ET Thursday, with the network down until roughly 4:30 p.m. A second outage struck early Friday and was resolved by late morning. A third began around 4:30 p.m. ET Friday and lasted until about 10:20 p.m. ET.

The first two stoppages came from the same gas-charging defect, exposed by a new “address balances” feature in v1.72. A transaction could be canceled for insufficient funds while the chain still deducted those funds, producing negative balances and crashing the validator step that reconciles accounts.

To restore service quickly, validators deployed an interim patch Thursday that the foundation described as carrying “a known issue with a low probability of causing a halt.” The team accepted that risk while developing a more durable repair; a variant of the known issue triggered the second halt Friday morning.

The third outage had a different cause. When validators restarted to install Friday’s fix, a latent bug in how the system preserves randomness settings between restarts surfaced. At the start of each epoch, validators run a setup for the random-number generator that some applications rely on. Too few validators were ready after the restart, so randomness switched off as designed, but a bug prevented validators from recording that decision and the epoch could not be closed, freezing the network.

Validators have since fixed both the gas-charging bug and the randomness-state bug, and the foundation reported that no user funds were at risk and no settled transactions were reversed when the network resumed. The team added a mechanism to force a stalled epoch closed and used it once during recovery. “As of now, validators have fully addressed the known issues caused by both the original gas-charging bug and the randomness-state bug, and network activity has resumed,” the foundation wrote.

The v1.72 upgrade also introduced gasless stablecoin transfers and the address balances feature, which created new gas-payment paths where the gas-charging defect appeared. The outages follow earlier downtime: a multi-hour stall earlier this year and a halt in November 2024 related to a validator crash bug.

The foundation said AI agents with access to production systems materially accelerated diagnosis during the incidents by querying validator logs and assembling metrics on demand across the three halts.

SUI traded around $0.88 on Sunday, down about 3.3% over the prior 24 hours. Sui is a Layer 1 blockchain developed by Mysten Labs, whose founders previously worked on Meta’s shelved Diem project.