Post-Mortem / Root Cause Analysis (RCA):
The downtime registered by this monitor between June 11th, 2026, and June 15th, 2026, is a false positive and does not represent an actual outage of the production Time Stamping Authority.

Technical Breakdown:
Root Cause: On June 11th, the production TSA timestamping certificate (used to sign time-stamp tokens) was renewed. However, the external monitoring probe's validation trust store was not simultaneously updated to recognize and trust the new certificate.

Behavior: During routine health checks, the probe requested a timestamp but failed to validate the signed response because it didn't trust the new TSA certificate yet. This triggered a false "DOWN" alert, even though the TSA infrastructure was fully operational, healthy, and correctly serving all production clients.

Resolution: On June 15th, the monitoring probe's trust store was updated with the new TSA certificate, immediately restoring the correct "UP" status.
The actual service availability during this timeframe remains at 100%. This incident was strictly limited to the monitoring system's verification layer.