Let's Encrypt: Delay updating OCSP responses

Let's Encrypt experienced a delay in updating OCSP responses, which fell behind the required schedule due to a misconfigured alert system. The issue was detected on September 5, 2021, and responses were served that did not comply with both the Microsoft Trusted Root Program and Baseline Requirements. The problem was resolved by September 8, 2021, after identifying the root cause and implementing technical mitigations. A full incident report was provided, detailing the timeline and corrective actions taken.

1. 2021-09-05 Internal monitoring detected OCSP response update delay.
2. 2021-09-07 Incident response began after awareness of the issue.
3. 2021-09-08 OCSP responses returned to compliance.
4. 2021-09-30 Review of existing alerts completed and changes deployed.
5. 2021-10-15 Bug closed as fixed.