Sui attributed the three mainnet outages to upgrade vulnerabilities, and secondly, the risk of outage was known before the implementation of one of the fixes.

CoinFeed reported on June 1st that, according to The Block, the Sui Foundation released an incident analysis report on the three recent mainnet outages, attributing the three network outages that occurred last Thursday and Friday to two separate vulnerabilities introduced in the v1.72 version upgrade. The first outage lasted approximately six and a half hours, while the second and third occurred on Friday morning and afternoon, respectively. The first two outages stemmed from a flaw in the transaction fee deduction method exposed by the "address balance" feature introduced in v1.72. When a transaction was canceled due to insufficient funds, the network would still deduct those funds, resulting in a negative balance that caused the validator node reconciliation process to crash. The Foundation acknowledged that the temporary fix urgently pushed out on Thursday carried known outage risks, and the team accepted these risks to quickly restore on-chain services, subsequently causing another network outage on Friday morning.