TL;DR:
Sui suffered three consecutive outages on its mainnet on May 28 and 29, leaving the network out of operation for more than 15 hours in total. The foundation overseeing the protocol’s development published a post-mortem analysis attributing the failures to bugs introduced in version 1.72 of its software.
The first outage began around 7:00 a.m. Pacific Time on Thursday and lasted nearly seven hours. The issue originated in the gas fee logic for transactions that combined the new address-balance system with traditional coin objects. When a transaction was cancelled due to insufficient funds, the fee routine still attempted to debit those funds, generating a negative overflow error that 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 team deployed a provisional fix at 1:30 p.m. on Thursday to restore the network as quickly as possible, but acknowledged that the patch had “a known issue with a low probability of triggering a new halt.” That scenario materialized Friday at 5:00 a.m., when a masked variant of the same bug bypassed the provisional patch. Validators adopted a more robust fix by 9:40 a.m. the same day.
The third outage, lasting approximately 43 minutes, was a direct consequence of the restart of validators required to install the second fix. Upon restarting, participation in the on-chain randomness protocol fell below the required threshold, disabling the mechanism. A latent bug prevented that disabled state from being persisted to disk, and when the epoch change occurred, transactions dependent on randomness accumulated in a paused queue for nearly six hours before being resolved.
The Sui Foundation confirmed that user funds were not at risk during any of the outages and that no confirmed transactions were reversed. It also outlined priority improvement areas, including better fault containment, greater resilience during epoch transitions, and additional investment in artificial intelligence agents for validator log diagnostics and analysis.
These events represent the third major reliability incident since the mainnet launched in May 2023, following a transaction scheduling failure in November 2024 and a consensus divergence in January 2026. With a total value locked of $519 million, Sui ranks 13th among the largest blockchains according to DefiLlama.
