Hidden Sequencer Glitch Uncovered: The Shocking Cause Behind Consecutive Outages Revealed

Ever wonder what happens when a tiny glitch in the blockchain’s nerve center brings an entire network to a screeching halt? Last week, Coinbase’s Base layer-2 network faced just that nightmare, thanks to a pesky sequencer bug that caused not one, but two outages—and left transactions stuck like a traffic jam that just won’t clear. The sequencer, a lonely captain steering the order of transactions, slipped up by holding on to some “stale journal state” following a rejected transaction. Talk about holding grudges! It halted block production for almost two hours, then again briefly, sending validators into a standstill and users into waiting limbo. While the Base team patched the problem and vowed to turbocharge testing and recovery methods, it serves as a sharp reminder: Even the biggest players can stumble over a digital pebble. Curious about the technical hiccups and what’s next for Base’s resilience? LEARN MORE.

A sequencer bug was responsible for two outages of the Coinbase layer-2 network Base last week, according to a post-mortem.

The Base engineering team said in a Saturday post-mortem that they identified a bug in sequencer block-building logic that allowed “stale journal state” to persist after a transaction validation failure.

“An invalid transaction was received by the block builder and failed during execution, as expected, but erroneously did not clear the journal state that contained the accounts and storage slots that had been accessed,” said the team.

The Base layer-2 network runs a single sequencer, which means one bug can stop everything. It is a centralized blockchain component that decides the order of transactions and has been responsible for outages on other layer-2 chains, including Arbitrum, OP Mainnet and zkSync Era.

On Thursday and Friday, Base mainnet experienced two block production outages, the first incident lasted 116 minutes and the second lasted 20 minutes.

There was a complete halt of new layer-2 blocks, and the sequencer and validator nodes could not progress past the invalid block until sequencing was restored.

The team fixed the outages by applying a patch to the sequencers to ensure the journal state was properly updated during execution.

However, mitigation took longer than expected “due to infrastructure conditions unrelated to the original bug,” they said.

There was also a “race condition” after the system reset, which prevented the sequencers from catching up, causing the second outage.

Going forward, the Base engineering team plans to improve protocol “fuzz testing,” which involves bombarding the system with large volumes of random, malformed, or unexpected inputs to find bugs, and building “graceful recovery” so that validator nodes don’t need manual restarts during future incidents.

Not the first outage for Base

It is not the first sequencer-related outage for Base, which stopped producing blocks for 17 minutes in September 2024 and for around half an hour in August 2025.

Base is the second-largest layer-2 network by total value secured, which is just under $11 billion, according to L2beat.

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