The Sui Foundation on Sunday published a detailed post-mortem of the three mainnet outages that took the Layer 1 blockchain offline across Thursday, May 28 and Friday, May 29, confirming what had remained unclear until now: the team knowingly deployed a fix with a recognized probability of causing another halt, and the network hit that exact failure the very next morning.
The disclosure adds a layer of transparency, but also raises fresh questions about how upgrade risks are managed on one of the highest-profile chains built by alumni of Meta’s shelved Diem crypto project.
Two Bugs, Three Halts, 18+ Hours of Downtime
According to Sui’s timeline, all three outages trace back to the v1.72 software release, which introduced a feature called address balances. This feature gives users a new way to store funds and pay for gas without using individual coin objects. It was part of a broader push to reduce friction, alongside the rollout of gasless stablecoin transfers.
The first halt began around 7 a.m. PT on Thursday and lasted until roughly 1:30 p.m. PT. It was caused by a bug in how the network handles “gas smashing,” a process that combines input coins into a single coin to pay transaction fees. The problem surfaced when a transaction was canceled for insufficient funds, but the gas smashing step still attempted to spend those same funds. That produced a negative balance delta that crashed the validator settlement process.
The Sui Foundation said this edge case could only be triggered when two transactions competed to spend from the same address balance simultaneously, and one had to be canceled to prevent an overdraft. The cancellation worked as intended, but the subsequent gas charge did not respect the cancellation.
The interim fix that broke things again
Here is where the post-mortem gets unusually candid. The core team proposed a fix on Thursday at around noon PT: simply skip gas smashing when a transaction is canceled with an InsufficientFundsForWithdraw error. Validators adopted it and the network came back by 1:30 p.m. PT.
But Sui’s own report states plainly that the team accepted the risk accompanying this fix to bring the network back as quickly as possible. The known shortcoming was that a transaction can be canceled for multiple reasons at once, and one error code can mask another. If the InsufficientFundsForWithdraw error was overridden by a different cancellation reason, the fix would be bypassed entirely and the same underflow crash would happen again.
That is exactly what occurred on Friday morning. The second outage started around 5 a.m. PT and was resolved by roughly 8:30 a.m. PT after the team deployed a more robust fix it had been building in parallel.
A third halt nobody saw coming
The network ran normally for about five hours after the Friday morning recovery. Then, at approximately 1:30 p.m. PT, the scheduled epoch change failed to complete, freezing the chain for a third time.
This halt had nothing to do with gas charging. It was triggered by a previously unknown bug in how validators preserve the state of their distributed key generation (DKG) protocol across restarts.
At the start of each epoch, Sui validators run DKG to set up the random beacon that certain applications depend on. DKG requires higher participation than regular consensus. When validators restarted to install Friday morning’s patch, not enough were ready for DKG, so it disabled itself.
That was expected behavior. What was not expected was that the failure status never got written to disk. As validators continued restarting, each one came back up unaware that DKG had already failed. Transactions requiring randomness could neither execute nor be canceled, and the queue backing up those transactions prevented the epoch from closing.
The fix had two parts: persist the DKG failure status across restarts, and add a mechanism for validators to force-close a stuck epoch at a coordinated point. Sui confirmed it used the force-close tool once during this recovery, and the network entered its next epoch normally with randomness restored. The third outage lasted from about 1:30 p.m. PT to 7:20 p.m. PT.
Sui emphasized that across all three halts, no user funds were at risk and no committed transactions were rolled back when the network resumed. The chain simply stopped processing new transactions during each window of downtime.
Sui acknowledges systemic weaknesses
The post-mortem closes with several forward-looking admissions that are worth noting. The Foundation acknowledged that gas charging logic has grown complex enough that edge cases like these are hard to rule out by inspection alone, and said the system deserves the same rigor as its Move virtual machine or Mysticeti consensus engine. It also flagged end-of-epoch resilience as too narrow, noting that the existing “safe mode” fallback did not cover the DKG failure scenario.
On the operational side, Sui disclosed that AI agents with access to production state helped speed up diagnosis across all three incidents by querying validator logs and assembling metrics on demand.
The Foundation said it plans to invest in failure containment strategies so that a future bug of this class would drop the problematic transaction rather than take down the entire network.
SUI Price Continues to Slide
SUI was trading around $0.87 at the time of writing, down roughly 13% from $1.04 recorded one week ago, according to CoinMarketCap data. The token’s market cap has slipped to approximately $3.48 billion. SUI hit an all-time high of $5.35 on January 6, 2025, meaning the token is now trading roughly 84% below that peak.
As The Crypto Times reported during the outages, $1.88 million in SUI positions were liquidated across the three halts, with long traders bearing the brunt of the losses.
A pattern that is getting harder to ignore
This was not an isolated event. Sui experienced a six-hour consensus divergence stall in January 2026, and before that, a validator crash bug knocked the network offline in November 2024. Three major outage windows in 2026 alone puts Sui in uncomfortable company, drawing comparisons to Solana’s early-era reliability struggles.
Sui, a Layer 1 blockchain built by Mysten Labs, has positioned itself as a scalable platform for DeFi, gaming, and institutional adoption. The very features meant to make the network more accessible, address balances and fee-free stablecoin transfers, created the new code paths where Thursday’s bug first appeared.
Whether the Foundation’s promised investments in failure containment and gas logic refactoring can break the cycle of upgrade-driven downtime will likely determine how much confidence developers and institutional users place in Sui going forward.
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