On April 2, according to official news, the zkSync team announced the cause of the outage on Twitter. Due to a failure in the block queue database, the block production stopped. Despite this, the server API was not affected. Transactions continue to be added to the memory pool and query services are normal. Although all components have comprehensive monitoring, logging and alerts, no alarms were triggered because the API was operating normally. When the accident occurred, the entire team was not online. The repair was implemented within 5 minutes. To solve similar problems, zkSync gives database monitoring agents a special role, enabling them to connect to the database and continuously collect metrics. At the same time, the team introduced an alert mechanism that will sound an alarm when the database monitoring agent fails or cannot establish a connection with the database. In addition, if the situation escalates seriously, the team on call will be notified immediately through multiple channels. But the only long-term solution is decentralization.