Sui mainnet back online after validator‑fix halts network for 6 hours

The Sui blockchain returned to normal operation on May 29 after validators applied a patched version to fix a critical bug introduced in the 1.72 software release [1]. The outage, which began on May 28, lasted almost six hours and prevented new checkpoints and transactions from being finalized [3].

Key takeaways

• A flaw in the gas‑charging logic of the 1.72 release caused the network to stall, freezing all transactions [1].
• Validators needed to upgrade more than two‑thirds of staked tokens before the chain could resume, a process that took nearly six hours [1].
• No user funds were lost and no confirmed transactions were reverted during the incident [2].
• The SUI token fell 6‑8% during the outage, trading around $0.88–$0.91 afterward [1][4].
• A third halt later that day stemmed from a separate epoch‑change bug affecting validator state persistence [2].

Bug in gas charging logic triggers first halt

The first outage started around 7 am PT on May 28 when validators running the new 1.72 code encountered an error in the gas‑charging module [2]. The update introduced “address balances” for fee payment, but when two transactions attempted to spend from the same balance simultaneously, one was cancelled while the network still tried to debit the fee, creating an impossible negative balance [2]. This crash halted block production and prevented any new checkpoints from being created, effectively freezing the network for several hours [1][3].

Subsequent outages and the final fix

A second interruption occurred on Friday morning when an edge‑case in the interim fix caused a different error code to bypass the cancellation guard, leading to another halt [2]. Validators applied a more comprehensive patch by 8:30 am PT, restoring activity temporarily. However, a third outage emerged around 1:30 pm PT during the scheduled epoch change. A latent bug prevented validators from saving the outcome of the epoch‑setup process, leaving them waiting indefinitely for a random value that never arrived, which stalled end‑of‑epoch logic [2][4]. The Sui Core Team confirmed that the network’s safety guarantees held, with no loss of funds or reversal of prior transactions [2].

Why it matters

The series of outages highlights the risks inherent in rapid protocol upgrades on high‑throughput Layer 1 blockchains. While Sui’s design prevented fund loss and maintained data consistency, the repeated multi‑hour downtimes have drawn investor attention, as reflected in a 6‑8% price dip during the incident and an 18% decline over the preceding week [1][4]. The team has outlined three focus areas—strengthening end‑of‑epoch resilience, refactoring gas‑charging logic, and improving failure containment—to reduce the likelihood of similar failures [2]. Continued monitoring of validator coordination and the effectiveness of the post‑mortem fixes will be crucial for restoring confidence in Sui’s reliability as it seeks to support DeFi, gaming, and stablecoin applications.