A bug in the sequencer block-building logic caused two outages on Coinbase’s Base layer-2 network. The engineering team identified and fixed the issue, but a race condition prolonged the second outage
On June 28, 2026, Coinbase's Base layer-2 network experienced back-to-back outages due to a bug in its sequencer block-building logic. These outages lasted for over two hours and halted new block production on the mainnet, causing significant disruptions.
The first outage occurred on Thursday, lasting 116 minutes, followed by a second shorter but equally disruptive incident of just 20 minutes on Friday. The engineering team traced the issue to an invalid transaction that failed during execution without clearing the journal state properly, leading to stale data persistence and subsequent block production failures.
Base's sequencer is its single centralized component responsible for ordering transactions, making it highly critical when functioning correctly but also prone to significant outages if a bug occurs. This problem has affected other layer-2 networks like Arbitrum, OP Mainnet, and zkSync Era in the past, highlighting the vulnerability of such systems.
The Base engineering team quickly applied a patch to fix the journal state issue during execution, aiming to prevent similar failures. However, they encountered additional challenges due to infrastructure conditions unrelated to the initial bug, which delayed recovery efforts further. A race condition after system reset also contributed to the second outage by preventing sequencers from catching up.
This incident is not Base’s first occurrence of a sequencer-related issue; previous outages in September 2024 and August 2025 lasted for 17 minutes and around half an hour, respectively. Despite these challenges, the engineering team plans to improve fuzz testing methods and implement graceful recovery strategies to mitigate future incidents.
Base remains the second-largest layer-2 network by total value secured at just under $11 billion according to L2beat. The outages underscore the risks associated with centralized components in blockchain networks but also highlight ongoing efforts to enhance resilience through better bug detection and mitigation techniques.
Source: Cointelegraph. Summarized and rewritten by the Vexoda Newsroom. This is market news, not financial advice.