Sui Blockchain Explains Major Outage, Claims Funds Were Safe

The SUI $1.79 24h volatility: 2.1% Market cap: $6.78 B Vol. 24h: $840.13 M blockchain suffered a roughly 6-hour network outage on Jan. 14. It halted block production and transactions across all validators.

In a post-mortem published on Jan. 16, the Sui Foundation confirmed that the stall was caused by an internal divergence in validator consensus processing. Validators were unable to certify the checkpoints, and the transactions timed out. However, SUI claims that the network’s safety mechanisms functioned as intended, preventing any loss of funds or inconsistencies in finalized states.

What Happened

According to the post-incident explanation, validators were unable to agree on a single checkpoint digest after reaching different conclusions about consensus commits. As a result, checkpoint certification stalled, halting transaction execution across the network. The issue was not caused by congestion, elevated transaction volume, or any external attack, Sui claims.
RPC read requests continued to serve the last certified state throughout the disruption, unless nodes were explicitly configured to stop serving data after prolonged inactivity. Sui reassures that no certified transactions were rolled back, no double-spends occurred, and user funds remained fully secure.

How the Fix Works

Engineers identified the point of divergence and deployed a fix that purged incorrect consensus data before safely replaying the affected portion of the consensus history. Validators operated by Mysten Labs first canaried the patch, confirming normal checkpoint production through logs and internal verification.

Following that validation, the broader validator set upgraded to the fixed binary, replayed consensus deterministically, and resumed checkpoint signing. Once a quorum signed the same checkpoint digest, certification restarted, and the network returned to normal operation.

Sui Price Impact and Community Reaction

Trading on exchanges and DeFi protocols briefly slowed, but resumed once the chain stabilized. The SUI token fell about 4% during the downtime, then rebounded to around $0.87 the next day.

On X, users remained concerned about the second major outage since the launch in 2023. “This marks the second major outage since launch, with still no public root-cause explanation,” X user 0xc06 wrote.

Among the L1 blockchains, Solana has suffered the most outages. Sui and Aptos follow with 2 and 1 since launch, respectively.

What’s next

The Sui team outlined several improvements aimed at reducing recovery time in similar edge cases:

• Earlier detection of checkpoint inconsistencies to pause consensus sooner.
• More automated operator tooling to identify and clean up divergent internal state.
• Expanded randomized and adversarial testing of consensus logic, including updated Antithesis configurations to consistently surface this class of bug.

Sui confirmed that all safety and consistency guarantees were maintained throughout the incident and that the network is now fully operational.

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