The Sui mainnet halted block production for nearly two hours. This Sui network outage marked the third major incident since the mainnet launch in May 2023. As a result, the SUI price fell by roughly 8% to around 0.91 USD.
Sui is a Layer-1 blockchain network that enables parallel transaction execution through an object-centric data model. Unlike sequential networks, independent transactions can settle simultaneously. Moreover, smart contracts run on Move, a programming language originally developed at Meta for the Diem project. Mysten Labs, the developer behind Sui, was founded in late 2021 by five former Meta engineers. Meta discontinued the Diem project itself in 2022 after regulatory pressure. Subsequently, the Sui mainnet went live in May 2023. The current incident is the second outage within five months. For example, the previous halt in January 2026 lasted nearly six hours. Including the first incident in November 2024, this marks the third major outage since the mainnet launch.
Sui network outage on 28 May: two hours without blocks
The halt began on 28 May 2026 around 14:29 UTC. Shortly afterwards, at about 14:36 UTC, the team identified the problem on the status page and started a fix. For nearly two hours, the network produced no new blocks. Meanwhile, transactions stayed paused network-wide during this period. As a precaution, the Walrus protocol also stopped its operations temporarily. This decentralized data storage protocol sits within the Sui ecosystem and has run a mainnet since March 2025.
The public RPC nodes, however, stayed operational. Therefore, read requests continued to receive answers. User funds were never at risk, because the blockchain simply produced no new blocks without compromising existing state data. The team did not initially publish the precise technical cause. Nevertheless, it announced a post-mortem. Meanwhile, alongside the outage, the SUI price fell by roughly 8% to around 0.91 USD.
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Architecture and background: Move, Mysticeti and parallel execution
Sui relies on an object-centric data model instead of classic account-based bookkeeping. As a result, this approach allows the parallel execution of independent transactions and delivers high throughput under normal load. The smart contract foundation is Move, a language that Sam Blackshear, today CTO of Mysten Labs, developed at Meta for Diem. Furthermore, the DAG-based mechanism Mysticeti has governed consensus since July 2024. Notably, it achieves sub-second finality under normal load. The validator set organizes itself through Delegated Proof-of-Stake.
Mysten Labs emerged in 2021 from a group of five former Meta engineers: Evan Cheng as CEO, Sam Blackshear as CTO, along with Adeniyi Abiodun, George Danezis and Kostas Chalkias. All five had previously worked on the Diem project, Meta's failed push for a global digital currency. In September 2022, the company closed a Series B round of 300 million USD. Specifically, FTX Ventures led the round at a valuation of over 2 billion USD.
The technical location of the previous problems is decisive. All three outages originated at the validator and consensus layer, not in the parallel execution model itself. Therefore, the object-centric design delivers the promised scaling. However, the weak point lies one layer deeper, where the validators must agree on new blocks.
Three outages, three causes: a pattern
The first major halt hit the network in November 2024 and lasted around two hours. The cause was an assertion bug in the congestion control logic of protocol v68. Specifically, it triggered a network-wide crash loop for transactions with zero execution costs. Mysten Labs fixed the error with version v1.37.4. Meanwhile, the trading platform Upbit suspended SUI deposits and withdrawals temporarily. In the crypto press, observers saw the incident as a stress test for the widespread "Solana killer" narrative.
The second outage on 15 January 2026 ran considerably longer at 5 hours and 52 minutes. This time, an edge-case bug existed in the consensus commit logic. Specifically, an optimization path produced a divergence between the validators under certain garbage collection conditions. Recovery proceeded in several stages, from diagnosis through a canary deploy on the Mysten Labs validators to the broad validator upgrade to the fix binary v1.63.3 and a final consensus replay. In the post-mortem of 16 January 2026, the Sui Foundation noted that no certified state forks occurred. Furthermore, the team rolled back no confirmed transactions.
The three incidents thus sit on three different layers: a bug in the congestion control logic, a consensus divergence, and a cause that initially remained unexplained in May 2026. User funds remained untouched each time, which clearly distinguishes network outages from exploits or smart contract errors. Nevertheless, the picture does not point to a single teething problem. Instead, it signals a recurring need for hardening in the validator infrastructure.
What Solana's stability path means for Sui
As a benchmark, the crypto industry regularly draws on Solana. The competing high-throughput network recorded several outages between 2021 and 2024, with the longest lasting around 19 hours in February 2023. Since February 2024, however, Solana has stayed without a major total outage, after targeted protocol fixes such as QUIC, stake-weighted Quality of Service and local fee markets took hold.
For Sui, this trajectory offers some orientation, although no free pass. Solana fundamentally resolved recurring bottlenecks around network load and transaction floods. In contrast, Sui's three outages trace back to three different causes. Therefore, a single patch is not enough, and broader hardening work at the validator level is required. The fact that user funds have so far always stayed safe is reassuring. Nevertheless, it does nothing to change the loss of trust as a cost factor for ecosystem growth.
