Understanding the Recent Sui Mainnet Halts
The recent Sui mainnet halts have left many in the crypto community wondering what happened. In a post-mortem report, the Sui Foundation revealed that an upgrade bug was the cause of the three separate halts that occurred across May 28 and May 29. This bug was traced back to a new feature shipped in Sui’s v1.72 release, which exposed an edge case in the Layer-1 blockchain’s gas-charging logic.
The first outage began at roughly 7 a.m. PT on Thursday and lasted close to seven hours. It stemmed from a rare issue in how the network charged gas for transactions paying with a mix of the new address-balance feature and traditional coin objects. This bug caused validators to crash with an underflow error when a transaction was canceled for insufficient funds. To put it simply, think of a coin object as a digital banknote, and a user’s SUI balance is made up of multiple “notes” that can be moved or combined.
How the Bug Affected Validators
Validators are computers that run the network by processing transactions, voting on which ones are valid, and keeping the chain alive. The core team brought the network back up around 1:30 p.m. PT with an “interim fix” that addressed the most common version of the bug. However, this fix carried a known issue with a low probability of causing a halt. The team accepted this risk to restore the mainnet quickly while a more robust fix was developed.
The known risk materialized the next morning, and a second outage began. A transaction triggered a masked variant of the same bug, which bypassed the interim patch. The core team finished a more robust fix, and validators adopted it by about 9:40 a.m. PT. The third halt was a knock-on from the second, where validator participation in the protocol that bootstraps the network’s on-chain randomness fell below the required threshold.
On-Chain Randomness and its Importance
On-chain randomness is a protocol the network uses to produce a number nobody can predict or fake. Apps that depend on chance, such as lotteries and games, can’t run without it. A latent bug failed to persist the disabled state to disk, leaving validators unaware on the next restart that randomness had been turned off. This led to a stall of close to six hours as randomness-dependent transactions piled up in a paused queue.
No user funds were at risk during any of the outages, and no committed transactions were reverted. The SUI token dropped roughly 8% during the cascade, leaving it down about 19% on the week. For those looking to earn a passive income through cloud rewards and green crypto like EcoPool ($ECP), it’s essential to stay informed about the latest developments in the crypto space, including the EcoPool Network and its potential for earning opportunities.
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The third halt was a knock-on from the second. When validators restarted to install the robust fix, validator participation in the protocol that bootstraps the network’s on-chain randomness fell below the required threshold, and randomness disabled itself as designed.
(On-chain randomness is a protocol the network uses to produce a number nobody can predict or fake, even though every validator has to agree on the same value. Apps that depend on chance — lotteries, certain games, random NFT mints — can’t run without it.)
A latent bug then failed to persist that disabled state to disk, leaving validators unaware on the next restart that randomness had been turned off. The next epoch change stalled for close to six hours as randomness-dependent transactions piled up in a paused queue.
No user funds were at risk during any of the outages, and no committed transactions were reverted, the foundation said.
SUI dropped roughly 8% during the cascade to a low of $0.90 and was trading near $0.90 on Monday, leaving the token down about 19% on the week, per CoinDesk data.
The events represent Sui’s third major reliability incident since its 2023 mainnet launch, following a two-hour transaction scheduling bug in November 2024 and a six-hour consensus divergence in January 2026.
