A sequencer bug was the cause of two outages on Coinbase’s Layer 2 network Base last week, according to a postmortem.
base engineering team said A post-mortem on Saturday identified a bug in the sequencer’s block construction logic that allowed “stale journal state” to persist after a failed transaction validation.
“An invalid transaction was received by the block builder and failed during execution as expected, but the journal state containing accessed accounts and storage slots was inadvertently not cleared,” the team said.
base layer 2 network Run a single sequencer. That means one bug can bring everything down. It is a centralized blockchain component that orders transactions and has been the cause of outages for other layer 2 chains such as Arbitrum, OP Mainnet, and zkSync Era.
Two outages occurred on the Base mainnet on Thursday and Friday, with the first incident lasting 116 minutes and the second incident lasting 20 minutes.
Sequencer and validator nodes were unable to advance beyond the invalid block until the new layer 2 block was completely stopped and the sequence was restored.
The team fixed the failure by patching the sequencer so that the journal state is updated properly during execution.
However, they said mitigation took longer than expected “due to infrastructure conditions unrelated to the original bug.”
Also, after a system reset, a “race condition” occurred and the sequencer couldn’t keep up, causing a second outage.
Related: Coinbase’s Base resumes block production after 2-hour outage
In the future, the Base engineering team plans to improve the “fuzz test” of the protocol. This includes bombarding the system with large amounts of random, malformed, or unexpected input to find bugs, and building in “graceful recovery” so that validator nodes do not need to be manually restarted in the event of future incidents.
This is not the first time Base has been out of service.
This is not the first sequencer-related outage for Base, which stopped producing blocks for 17 minutes in September 2024 and for about 30 minutes in August 2025.
Base is the second largest Layer 2 network by total amount secured, at just under $11 billion. According to To L2 beat.
magazine: AI is bringing banking to the unbanked in Africa… faster than cryptocurrencies
