The Sui mainnet suffered three separate outages over May 28–29, 2026, and the Sui Foundation has published a detailed post-mortem tracing all failures to bugs introduced in the v1.72 network upgrade. The root cause was a new Address Balances feature that interacted dangerously with existing gas-charging logic, exposing successive flaws as each fix created the conditions for the next problem.
The first halt began on May 28 after a rare transaction case that combined the new address-balance system with legacy coin objects. When two transactions competed for the same balance and there were insufficient funds, one was correctly canceled—but the gas-charging mechanism still attempted to debit the canceled transaction’s fees. This resulted in a negative balance and crashed validator nodes, taking the network down for roughly six and a half hours. Validators restored service with an emergency patch, though the Foundation acknowledged the patch carried a known low probability of triggering the same crash under a slightly different cancellation path.
The second outage materialized the next morning when exactly that scenario occurred. Another transaction followed a cancellation path that bypassed the temporary fix, causing a new crash. A stronger permament fix was deployed by about 9:40 a.m. PT and the network returned to operation after about three and a half hours of downtime.
However, a third, entirely unrelated bug emerged when validators restarted to apply the Friday morning fix. Sui’s distributed key generation protocol requires a minimum validator participation threshold to maintain the randomness system; the restart temporarily dropped participation below that level, and randomness automatically disabled itself—exactly as designed. The flaw was that the disabled state was never saved to disk. When validators came back online, they had no record that randomness was turned off and continued queuing transactions that depended on it, stalling the epoch-end process indefinitely. The third halt lasted nearly six hours.
The permanent fix resolved both the gas-charging underflow and the randomness-state persistence problem, and added a mechanism for validators to force‑close a stuck epoch. No user funds were endangered and no finalized transactions were rolled back. The Foundation stressed that AI-powered log analysis significantly accelerated debugging and committed to hardening gas-charging code quality, epoch resilience, and failure containment before future upgrades.
