Sui has revealed that two software bugs introduced in its v1.72 upgrade were responsible for three separate mainnet outages across May 28 and May 29, prompting validators to deploy major fixes to restore network stability.
Key Takeaways
- Sui confirmed that bugs introduced in the v1.72 upgrade caused three network outages within two days.
- The issues were linked to a new Address Balances feature, gas processing logic, and a separate randomness state bug.
- The network has since implemented fixes, with the foundation saying no user funds were lost and no finalized transactions were reversed.
- SUI declined following the outages as investors weighed fresh concerns about network reliability.
What Happened?
The Sui Foundation has published a detailed post mortem explaining how a pair of software bugs introduced in the blockchain’s v1.72 release led to three separate mainnet outages over a 48 hour period.
According to the foundation, the incidents were tied to the rollout of the Address Balances feature, a new functionality designed to let users store funds and pay gas fees directly from account balances instead of relying solely on coin objects. While the feature aimed to improve user experience, it unexpectedly exposed flaws in the network’s existing gas processing and consensus systems.
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
How the First Two Outages Unfolded?
The first outage began around 7 a.m. PT on May 28 and lasted for nearly seven hours. Sui developers traced the disruption to an edge case involving transactions that used both the new Address Balances feature and traditional coin objects.
Under certain conditions, transactions that failed because of insufficient funds were still processed as though gas fees had already been spent. This created negative balances that validators were unable to reconcile, ultimately causing validator crashes and bringing the network to a halt.
To restore operations quickly, the core team introduced an interim fix and brought the network back online later that day. However, developers acknowledged that the temporary solution contained a known low probability issue that could potentially trigger another outage.
That risk became reality on May 29 when a second outage occurred. A different variation of the same gas processing bug bypassed the interim fix, forcing developers to complete and deploy a more comprehensive solution.
The foundation explained that in some cases the insufficient funds error could be masked by another cancellation reason, allowing the bug to slip past the temporary patch and once again disrupt network operations.
A Separate Bug Triggered the Third Halt
Although the stronger gas processing fix resolved the primary issue, the recovery process exposed another dormant bug.
As validators restarted their nodes to install the updated software, participation in Sui’s on chain randomness protocol temporarily fell below the required threshold. The system automatically disabled randomness as designed.
However, a latent software error prevented validators from properly saving that disabled state during restart. As a result, validators failed to recognize that randomness had been turned off, creating problems during the next epoch transition.
The issue caused the network to stall for nearly six hours as randomness dependent transactions accumulated in a paused queue. Sui said this third outage was not directly caused by the original gas processing problem but was uncovered during efforts to resolve the earlier disruptions.
No User Funds Were Affected
Despite the repeated outages, the Sui Foundation emphasized that no user funds were at risk throughout the incidents.
The foundation also stated that no committed transactions were reverted after network operations resumed. Validators successfully restored service following the deployment of the final fixes addressing both the gas processing and randomness state bugs.
According to the post mortem, all known issues linked to the incidents have now been resolved, and the network is operating normally.
Reliability Questions Return as SUI Falls
The outages renewed scrutiny of Sui’s reliability, particularly because they mark the latest in a series of network disruptions since the blockchain’s launch.
Sui previously experienced a validator related outage in November 2024 and another major disruption in January 2026 that was linked to a consensus divergence bug.
Market reaction was swift. The SUI token fell from levels near $0.99 before the outages to around $0.90 during the disruption period, reflecting investor concerns about network stability.
Looking ahead, the foundation said it plans to strengthen failure containment systems, improve end of epoch handling, expand fault isolation capabilities, and introduce more AI assisted diagnostics. One key goal is to ensure future software failures can be isolated to specific transactions rather than forcing the entire network offline.
CoinLaw’s Takeaway
In my experience, outages themselves are not what concern investors most. What matters is how quickly a blockchain identifies the root cause, communicates transparently, and implements lasting fixes. Sui deserves credit for publishing a detailed explanation and acknowledging that both the original bug and an imperfect emergency patch contributed to the disruptions.
I found the planned focus on fault isolation particularly important. If Sui can prevent a single faulty transaction or software issue from halting the entire network, it could significantly improve confidence among users, developers, and institutions. Still, after multiple reliability incidents in recent years, the network will likely face greater scrutiny whenever future upgrades are rolled out.
