Coinbase’s Base mainnet went down for nearly two hours Thursday after a faulty block froze the chain’s sequencer and halted all new block production.
Key Takeaways:
Base mainnet block production stalled for nearly 2 hours on June 25 after block #47,806,542 caused a consensus failure.Coinbase’s Base team confirmed all funds are safe, with sequencing restored by 17:51 UTC and monitoring ongoing.Base’s Beryl hard fork, introducing the B20 native token standard, remains on schedule for its 18:00 UTC activation window.In OP Stack terminology, the event is classified as an “unsafe head stall.” That means the sequencer stopped advancing new blocks entirely. The unsafe head refers to the latest sequencer-produced blocks that have not yet been posted to Ethereum’s layer one (L1) for finalization.
Timeline:
16:03 UTC: Block production flagged as unhealthy; investigation begins. 16:52 UTC: Engineers identify block #47,806,542 as the problematic source. 17:21 UTC: Consensus issue isolated; internal sequencer and nodes show preliminary recovery. 17:51 UTC: Block sequencing resumes; internal nodes begin syncing correctly. 17:58 UTC: Blockbuilding confirmed healthy; network enters monitoring phase. What It Means for UsersFunds are not at risk. Unsafe head stalls occur before blocks are batched and submitted to Ethereum L1, so there is no exposure to permanent loss or meaningful chain reorganizations.
Beryl Upgrade Still on Track What Comes NextBase engineers are continuing to investigate the root cause of the invalid block and plan to publish a full post-mortem once the review concludes. The status page at status.base.org and block explorer basescan.org remain the primary monitoring resources.
