Sui Deployed a Fix It Knew Could Crash the Network — Then the Network Crashed

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• Sui said three mainnet halts on May 28 and 29 came from upgrade-linked gas logic and randomness-state bugs.

• Sui’s first quick fix carried a known halt risk, which appeared when the network stopped again on May 29.

The Sui Foundation has traced three mainnet halts to bugs linked to its latest network upgrade, including one outage that followed an interim fix the team already knew carried a small crash risk. The incidents affected Sui Mainnet on May 28 and May 29, after validators adopted changes tied to release 1.72.

The Foundation said the first two outages came from gas-charging logic linked to the new address balances feature. That feature gives users another way to store funds and pay transaction fees without relying only on coin objects. However, an edge case appeared when transactions used hybrid gas payments, which combine address balances and coin objects.

The first halt began around 7 a.m. PT on May 28 and ended near 1:30 p.m. PT. Sui said a transaction could fail due to insufficient funds, but the network could still try to spend the same balance during gas processing. That created a negative balance during settlement and caused validators to crash.

Following last week’s outages related to the 1.72 release, the Sui Core Team has completed an investigation and incident review, detailing what happened and the steps taken by validators to restart the network.

— Sui (@SuiNetwork) May 31, 2026

The core team proposed a quick fix to restore activity while engineers worked on a stronger solution. The temporary fix had a known issue with a low chance of causing another halt. The team accepted that risk to bring the halted network back faster.

That risk later appeared. On May 29, the network hit a variant of the same issue and stopped again. The second outage began around 5 a.m. PT and ended near 8:30 a.m. PT. By then, the team had nearly completed a broader fix, and validators adopted it later that morning.

Upgrade Bugs Trigger Three Sui Halts

The third outage came from a different bug. It appeared during the next scheduled epoch change after validators restarted to install the Friday morning fix. Sui validators run a distributed key generation process at the start of each epoch to support on-chain randomness for applications that need it.

After the restart, too few validators took part in that process, so randomness switched off as designed. However, a separate bug stopped validators from saving status correctly. When validators restarted, they did not remember that randomness had already failed for the epoch.

That failure left randomness-linked transactions stuck. End-of-epoch logic needed to clear the pending queue before closing the epoch, but the system waited on a process that could no longer finish. The third halt began around 1:30 p.m. PT on May 29 and ended near 7:20 p.m. PT.

Validators later fixed both the gas-charging bug and the randomness-state bug. User funds never faced risk during the outages, and the network did not reverse committed transactions after activity resumed.

The Foundation added a mechanism that allowed validators to close the stalled epoch at a coordinated point. Validators used that tool once during recovery, then the network moved into the next epoch and restored randomness.

Sui Foundation also noted that AI agents helped engineers review validator logs, check cluster state, and gather metrics during the recovery work.

The review places renewed attention on upgrade risk for Sui, a Layer 1 blockchain built by Mysten Labs. The network has seen earlier downtime, including a January stall and a November 2024 halt linked to a validator crash bug.

Previously, Sui founder Adeniyi Abiodun said SUI will make stablecoin transactions private by default, showing only key details to the sender and receiver. The feature aims to protect payment history from public view, with plans to expand privacy tools to other assets on Sui later.

SUI traded near $0.87 after the incidents, down about 3% over 24 hours. For now, SUI network activity has resumed, while future work will focus on failure containment so one bad input does not halt the wider chain.