Sui Network Hit by Three Sequential Outages Causing Combined Downtime of 15 Hours

Third halt linked to fix

A series of three outages took down the Layer 1-protocol built by former Meta engineers starting from 28 May, including a third breakdown that was triggered by the firm’s own emergency repairs to the prior outages.

Sui's native token, SUI, which fell as much as 5% during the first freeze, came under fresh selling pressure. Over the 48-hour cumulative crash, the token sank 8%, according to CoinMarketCap, as the network's market cap dropped to $3.59bn from approximately $3.96bn prior to the incidents.

User funds safe

"During the outages, no user funds were at risk, and the network did not revert any committed transactions when it resumed," Sui said in a lengthy 31 May report on the incidents.

The cascading halts occurred on 28 May from 14:00-20:30 UTC, 29 May from 12:00-15:30 UTC, and from 29 May 20:30 into the following day at 02:20 UTC. The first outage was when the core validator network of Mysten Labs experienced a consensus breakdown, stalling all block production and network settlement.

The second breakdown was related to the first. Sui had recently rolled out a new feature involving "address balances." The first halt was linked to a crash bug in the gas charging logic introduced by the 1.72 release.

Gas logic bug

The issue arose from a software defect in the internal calculator built into the Sui blockchain that determines exactly how much transaction fee, or gas, a user must pay to execute an action on the network. 

A bug inside the code caused the network's gas-charging system to crash whenever it tried to process specific transactions tied to the address balances feature. "Changing gas logic is a delicate operation," Sui noted. 

To resolve Thursday's six-hour crash quickly, Sui's team deployed an interim patch, knowing that there were flaws. "One such shortcoming is that a transaction may have multiple reasons for cancellation, and one reason can override the others," Sui said. 

Epoch change failure

In this case, the flaw was triggered, bringing down the network for the second time in as many days. Sui said that normal operations resumed for about four hours afterward, but at 20:30 UTC, a scheduled system reset, known as an epoch change, failed, freezing the blockchain for the third time.

This occurred from a disabled Distributed Key Generation (DKG), which is the network’s random-number generator. It had switched itself off as a built-in safety measure and had been triggered by Sui because the earlier emergency repairs forced all the network validators to restart.

During the validator rebooting, they missed the tight deadline to participate in setting up the random-number system, and the network automatically disabled the tool as voter turnout wasn’t high enough.

Post-mortem findings

Sui offered some sober assessments following the incidents, including a pledge to overhaul its complex gas-charging code and apply the same strict code quality standards as its core consensus engine. 

It also will invest in failure containment strategies and permanent "force-close" mechanisms that allow validators to manually override stuck network states or simply drop a single crashing transaction rather than letting it take down the entire blockchain.

Help from AI agents

Sui noted that specialised AI agents with access to production state, capable of interactively querying validator logs, inspecting cluster state, and assembling metrics on demand "materially accelerated diagnosis" during the outages. 

It said that the AI tools are "worthy of continued investment."

Sui and its much larger chief rival Solana are major players in the decentralised finance system, processing transactions as the global financial layer of the internet. While outages are not uncommon, prolonged and repeated downtime erodes trust in the protocol and potentially traps billions of institutional capital.