On August 6th, 2024, our Stacks Blockchain testnet node pool experienced an outage due to a block height synchronization issue. This was caused by a transaction stuck in one Bitcoin node’s mempool, which failed to propagate to other nodes, resulting in the block height not advancing for 90 minutes. To mitigate the issue, we manually copied the missing transactions between Bitcoin nodes, restoring normal service shortly after. Moving forward, we will implement an automation script to prevent similar occurrences.