The Layer 1 blockchain blamed two stoppages in as many days on its 1.72 upgrade and said validators have now deployed a permanent fix. SUI slid about 15% in the past seven days.
Sui, the 31st-largest cryptocurrency by market value, said its mainnet is processing transactions again after two halts in two days knocked the Layer 1 blockchain offline, with validators rolling out what the team described as a long-term fix.
Activity resumed and transactions are “flowing normally,” Sui said in a post on X on Friday. The first stall, on Thursday, lasted close to six hours, according to the network’s status page. A second halt hit Friday morning after an interim patch relapsed. SUI fell roughly 5% over the past 24 hours to around $0.92, according to data from CoinGecko.
The repeated downtime cuts against Sui’s pitch as a high-speed network built to handle financial transactions at scale. It marks the chain’s second major outage of 2026 and renews questions about reliability that have dogged faster Layer 1s, most notably Solana, which suffered a string of stoppages in earlier years.
Bug Froze Blocks
Sui traced both incidents to the interaction between its 1.72 release, which introduced a feature called Address Balances, and the network’s gas-charging logic, the code that meters transaction fees. A crash bug in that logic froze block production and checkpoint updates, halting transactions across the chain.
The bug surfaced first on Thursday. Validators deployed an interim fix to bring the network back, but Sui said the patch “had a known issue with a low probability of causing a halt.” On Friday morning, the network hit a variant of that issue and stalled again.
No Funds Lost
Sui said validators have since implemented a long-term solution that fully addresses the underlying bug, and that the network is operating normally.
No user funds were lost in either incident, and certified transactions were not rolled back, according to the network. Public access points that let wallets and applications read the chain stayed online during the outages, so users could still view balances even as transfers were frozen. Several apps on Sui, including lending protocols, paused deposits and withdrawals as a precaution.
Downtime Pattern
Sui launched its mainnet in May 2023, developed by Mysten Labs, a company founded by former Meta engineers who worked on the Diem blockchain project. The network is designed for subsecond finality and low fees.
It has stalled before. The chain went offline for about six hours in January and for roughly two and a half hours in November 2024, when validators were caught in a crash loop.
The outages land during a stretch of expansion for the ecosystem. Sui’s total value locked hit a record $2.6 billion in October, and the chain recently added USDsui, a native stablecoin issued by Stripe subsidiary Bridge.
What’s Next
Sui said a detailed incident review is forthcoming. Validators on the mainnet were still listed as operating under degraded performance after the restart, according to the network’s status page.
