Sui Network Outages Expose Gas-Charging Bug and Randomness Failure

Sui, a leading Layer-1 blockchain, experienced three separate mainnet outages on May 28 and May 29, 2026, after a series of software bugs triggered network-wide disruptions. According to a post-mortem released by the Sui Foundation, each attempted fix either revealed or contributed to another failure, resulting in a cascading reliability incident that temporarily halted blockchain operations.

The first outage started around 7 a.m. PT on May 28 and lasted nearly seven hours. The issue originated from a rare flaw in Sui’s gas-charging mechanism involving transactions that used both the newly introduced address-balance system and traditional coin objects. When a transaction failed because of insufficient funds, validators encountered an underflow error after the gas-processing routine attempted to spend the same funds again, causing network nodes to crash.

In Sui’s architecture, balances are stored as multiple coin objects rather than a single account balance. These digital assets can be combined to pay transaction fees, making gas accounting more complex. Validators, which are responsible for verifying transactions and maintaining network consensus, were directly affected by the bug.

Developers restored the network later that day using an interim fix designed to address the most common version of the problem. However, the solution contained a known low-probability risk. That risk materialized early on May 29 when a different variation of the bug bypassed the patch, triggering a second outage. A more comprehensive fix was subsequently deployed and adopted by validators.

The third disruption occurred during the restart process. Validator participation dropped below the threshold required to support Sui’s on-chain randomness protocol, causing it to disable itself. A separate latent software bug then failed to save that disabled state, leading to further issues during the next restart and delaying an epoch transition for nearly six hours.

The Sui Foundation emphasized that no user funds were lost and no finalized transactions were reversed. Despite this, the incident weighed heavily on market sentiment. SUI fell roughly 8% during the outage period and traded near $0.90 afterward, leaving the cryptocurrency down approximately 19% for the week.

The May 2026 outage sequence marks Sui’s third major reliability incident since its mainnet launch in 2023, following a transaction scheduling issue in November 2024 and a consensus divergence event in January 2026.