Sui has released a detailed explanation of what caused its six-hour network outage on January 14, and the good news is this: user funds were never at risk.
According to Sui, the outage happened because of a consensus bug among validators. In plain terms, parts of the network disagreed with each other, which forced the system to pause to protect itself.
In a blog post published on January 16, the Sui team explained that the problem had nothing to do with heavy traffic, hacking attempts, or security breaches. It was an internal issue, and safety systems worked exactly as they were supposed to.
So what actually went wrong?
An edge-case bug caused validators to process certain conflicting transactions differently. Because of that, they started creating different versions of checkpoint data. Since the network couldn’t reach the required agreement, it was impossible to certify a new checkpoint.
Once validators noticed that a large amount of stake was signing conflicting data, the network shut itself down by design. This pause prevented the blockchain from locking in an inconsistent or broken state, even though it meant transactions had to stop.
During the outage, users couldn’t send transactions, and submissions timed out. However, read-only access still worked, meaning users could see the last confirmed state of the network. No confirmed transactions were reversed, and no chain splits happened.
Roughly $1 billion worth of on-chain value was temporarily frozen during the six-hour halt, but everything remained intact.
How the network recovered
Once the issue was identified, validators removed the bad consensus data, fixed the commit logic, and replayed the chain from the point where the problem started.
Mysten Labs validators tested the fix first through a controlled rollout. After that worked, the rest of the validator network upgraded and resumed checkpoint signing. Normal operations were fully restored later the same day.
Sui said the incident proved that its safety-first design works. The system chose consistency over speed, which helped avoid deeper problems. Still, the team admitted that recovery needs to be faster.
To improve things going forward, Sui plans to automate more validator operations, expand testing to catch rare consensus bugs before they reach the mainnet, and improve early detection of checkpoint issues.
This was the second major disruption for Sui since launching in 2023, following a smaller incident in late 2024. Despite the outage, the SUI token saw only minor price movement, suggesting most traders viewed the problem as technical and temporary—not a long-term threat.
In short, the network paused to protect itself, funds stayed safe, and Sui is now focused on making sure future recoveries happen faster and smoother.
