Base, a layer-2 network backed by Coinbase, found that a sequencer software bug caused two network outages that stopped block production last week.
The outages lasted 116 minutes and 20 minutes, temporarily blocking transactions until engineers fixed the problem. Base says the issue is now resolved and new safeguards are being added to help prevent similar problems in the future.
In a technical post-mortem published on Saturday, the Base engineering team said the problem started with an error in the sequencer’s block-building logic.
An invalid transaction failed as expected, but the software kept old journal data instead of clearing it. This stopped the sequencer from moving past the faulty block and halted block production.
Base currently uses just one sequencer to order transactions, so any major failure in that part can temporarily stop the network. Other layer-2 blockchains like Arbitrum, OP Mainnet, and zkSync Era have had similar sequencer outages.
On Thursday and Friday, Base mainnet experienced two block production outages. The first incident lasted 116 minutes and the second lasted 20 minutes.
Block production halted completely, 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 sequencer to ensure the journal state was properly updated during execution.
On June 25 and 26, Base mainnet experienced two block production outages, both caused by the same underlying bug in the block builder logic.
We’ve identified and fixed the root cause, and have communicated the post mortem to OP chains as feedback.
All funds were safe… pic.twitter.com/eArnK12AgZ
— Base Build (@buildonbase) June 27, 2026
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