On February 4, 2019, Elastic Cloud experienced significant service disruptions in the AWS us-east-1 region, affecting Elasticsearch and Kibana access for customers due to issues during a routine patching procedure of the coordination layer's ZooKeeper ensemble. The incident led to degraded performance and outages from 02:50 to 09:28 UTC for Elasticsearch and until 18:44 UTC for Kibana, caused by a combination of high load, instability in the ZooKeeper observer layer, and internal TLS proxying service errors. The root cause was traced to unfamiliar errors encountered during maintenance, compounded by insufficient service metrics and a set of unexpected issues. Resolution involved re-establishing quorum in the ZooKeeper ensemble, stabilizing the observer layer, and addressing Kibana's connection leaks and request amplification. Elastic Cloud has since implemented various engineering and process improvements to enhance system resilience and prevent future incidents, including reducing ZooKeeper data size, optimizing proxy health-check logic, and improving internal logging and monitoring strategies.