Everything Is Healthy and Nothing Works
At 00:00 UTC the mobile app stopped working for every user: SSL handshake failed. The web app shows a browser interstitial about an invalid certificate. Every dashboard is green — instances healthy, all load balancer targets healthy, application error rate zero, latency normal. The first thing the on-call engineer checked, an internal monitoring endpoint, returned 200 OK.
Pull evidence
One item at a time, and nothing here tells you which one matters. Deciding what is worth looking at is most of the diagnosis.
0 of 9 inspected. You are not required to open all of them — a real investigation is judged on how few you needed.
What is your diagnosis?
Commit to one. Nothing below is shown until you do.
Guessing wrong and being told exactly why is the point of this page. Reading the answer first is not practice.