Base Network Outage Review: Two Consecutive Downtimes Caused by a Sequencer Bug

According to official announcements, the root cause of two consecutive outages last week on Base, Coinbase’s Layer 2 network, has been identified as a software bug in the sequencer’s block-building logic. Base’s engineering team explained that when an invalid transaction fails to execute, the associated temporary state (Journal State) should be cleared, but a software flaw incorrectly retained the old state, preventing the sequencer and validator nodes from producing new blocks. On June 26, Base’s mainnet experienced two consecutive block production outages as a result: the first lasted 116 minutes, and the second 20 minutes. The team noted that while a patch fixed the sequencer state update issue, a race condition emerged after the system restart, preventing the sequencer from resynchronizing in time and triggering the second outage. Additional infrastructure issues also prolonged the total recovery time. Base said it will strengthen protocol fuzz testing to improve its ability to detect vulnerabilities in edge-case input scenarios, and optimize network recovery mechanisms to eliminate the need for manual validator node restarts during future similar incidents. Notably, this is not the first time Base has suffered a sequencer-related outage: the network previously faced outages of roughly 17 minutes in September 2024 and 30 minutes in August 2025. As of now, Base remains the second-largest Ethereum Layer 2 network by total value secured (TVS).