In this blog, I am going to share a real-world debugging case study where a routine Percona XtraDB Cluster node restart led to an unexpected failure. I will walk through what we observed, what we checked, and how we ultimately identified the root cause.

Let’s see how the maintenance goes. It was supposed to be a simple restart. The kind you’ve done a hundred times. You SSH in, run the maintenance, bring the node back up, and go grab a coffee. Except this time, the coffee went cold on the desk… because MySQL refused to start.

The Problem

The error log of Percona XtraDB Cluster (8.0) had the following information:

2025-11-05T05:26:10.982984Z 0 [ERROR] [MY-000059]   [Server] SSL error: Unable to get certificate from '/var/lib/mysql/server-cert.pem'.
2025-11-05T05:26:10.983030Z 0 [Warning] [MY-013595] [Server] Failed to initialize TLS for channel: mysql_main. See below for the description of exact issue. …