Sui Mainnet Back Online After 3 Outages Triggered by Software Upgrade Bugs

Sui (SUI) Mainnet has resumed normal operations after three separate network outages over two days, all tracing back to bugs introduced in the recent 1.72 software release.

The Sui network mainnet halts occurred on May 28 and May 29, 2026, and temporarily suspended all network activity while validators coordinated fixes.

Sui Mainnet Outage: What the 1.72 Upgrade Broke

The first outage began around 7 am PT on Thursday and lasted until approximately 1:30 pm PT. The 1.72 release introduced a new way for users to pay transaction fees using so-called address balances.

A bug appeared when two transactions tried to spend from the same address balance at the same time, and one of them got cancelled. Even though the transaction was cancelled, the network still tried to debit the fee. This resulted in an impossible negative balance and crashed the system.

Validators adopted an interim fix to quickly restore the network, but the team acknowledged it had a known edge case. That edge case materialized Friday morning around 5 am PT. A different error code overwrote the original cancellation reason and bypassed the guard, which triggered a second halt. The team deployed a more complete fix by 8:30 am PT.

The third outage, from approximately 1:30 pm to 7:20 pm PT on Friday, had a separate cause. Each time Sui moves into a new epoch, validators run a setup process. This process generates a shared random value used by certain transactions. Validators restarted to adopt the Friday morning fix.

However, not enough of them participated in this process, so it was disabled for that epoch. Due to a latent bug, however, that outcome was never saved to disk. When validators restarted, they had no memory of the failed setup and kept waiting for a result that would never come. End-of-epoch logic stalled, and the network halted a third time.

Throughout all three incidents, the Sui Core Team confirmed that no user funds were at risk and the network did not revert any previously confirmed transactions. The SUI token price trades around $0.88. It is down 2.57% in the past 24 hours, with a market cap of roughly $3.5 billion at rank 32.

The team has since outlined three areas for investment: strengthening end-of-epoch resilience, refactoring gas charging logic to make it more modular and testable, and building failure containment so a single bad input cannot halt the entire network. The incident follows Sui’s earlier $10 million security commitment after the Cetus hack. It underscores the ongoing scrutiny of Sui outages and the chain’s ability to quickly resolve network bugs.

Whether the speed of this week’s recovery and the transparency of the post-mortem shifts sentiment ahead of the next epoch upgrade remains to be seen.