Sui traces three mainnet halts to upgrade bugs, including a fix it knew carried halt risk

Sui Foundation on Sunday published its review of the outages that knocked its blockchain offline three times across Thursday and Friday, attributing the disruptions to two distinct bugs introduced with its v1.72 software release.

The account confirms a third halt and answers a question left open in about whether the incidents shared a root cause.

According to , the first halt began around 10 a.m. ET Thursday and ran until roughly 4:30 p.m., somewhat longer than the 5 hours and 55 minutes The Block reported from the status page at the time. A second outage hit early Friday and was resolved by late morning, and a third began around 4:30 p.m. ET Friday and lasted until about 10:20 p.m.

The first two halts stemmed from the same flaw in how Sui charges transactions for gas, exposed by the "address balances" feature that v1.72 introduced. The foundation said a transaction could be canceled for insufficient funds while the network still went on to spend those same funds, producing a negative balance that crashed the step where validators reconcile accounts.

What turned one outage into two was the patch itself. The foundation said the interim fix it rushed out Thursday carried a "known issue with a low probability of causing a halt," a risk the team accepted to bring the chain back quickly while a more durable fix was built. On Friday morning, the network hit a variant of that issue and halted a second time.

The third halt had a different and previously undisclosed cause. It was triggered when validators restarted to install Friday morning's fix, which tripped a latent bug in how the network preserves its randomness settings between restarts.

At the start of each epoch, Sui's validators run a setup process for the random number generator that some applications rely on. The foundation said too few validators were ready for that process after the restart, so randomness switched off as designed, but a bug meant validators failed to record that decision and could not close out the epoch, freezing the network a third time.

Sui said validators have since fixed both the gas bug and the randomness bug, that no user funds were ever at risk, and that no settled transactions were reversed when the network came back. It also said it built a mechanism to force a stalled epoch closed, which it used once during the 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 in its report.

The foundation also said AI agents with access to its production systems materially sped up the diagnosis, querying validator logs and assembling metrics on demand across the three incidents.

The bugs also surfaced in the parts of the upgrade meant to make Sui easier to use. The Block previously reported that v1.72 added address balances, which move the network away from its prior accounting model, and gasless stablecoin transfers. Those features reduce friction for users, and they also created the new gas-payment paths where the fault appeared.

The outages extend a run of upgrade-related downtime for Sui. The Block covered a roughly six-hour stall in January, and the network also halted in November 2024 after a validator crash bug.

SUI was trading around $0.88 on Sunday, down roughly 3.3% over the past 24 hours. Sui is a Layer 1 blockchain built by Mysten Labs, whose founders came out of Meta's shelved Diem crypto project.

The foundation said it plans to invest in containing failures so that a future bug of this kind would drop the offending transaction rather than halt the whole network.