Outage in Let's Encrypt
API Degraded Performance
Resolved Minor
June 18, 2026 - Started about 21 hours ago
- Lasted about 13 hours
Incident Report
Summary AI Generated
Let's Encrypt's production ACME API (acme-v02.api.letsencrypt.org) experienced degraded performance for approximately 12.7 hours, causing clients to receive 400 and 500 error responses during certificate issuance. The root cause was a networking issue between Let's Encrypt's two high-assurance data centers, which was escalated to their upstream ISP for investigation. Stabilization measures were applied early in the incident while the underlying network issue continued to be investigated.
Let's Encrypt's production API is experiencing degraded performance. Clients may encounter 400 and 500 error responses. We are actively investigating the issue.
Components affected
Let's Encrypt acme-v02.api.letsencrypt.org (Production)Trusted by 1,000+ teams
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Latest Updates ( sorted recent to last )
about 21 hours ago - at 06/18/2026 04:04PM
Let's Encrypt's production API is experiencing degraded performance. Clients may encounter 400 and 500 error responses. We are actively investigating the issue.
about 21 hours ago - at 06/18/2026 04:35PM
We have taken measures to stabilize API performance while we investigate networking issues between our two high assurance data centers.
about 18 hours ago - at 06/18/2026 07:40PM
We are continuing to investigate degraded performance and elevated error rates.
about 13 hours ago - at 06/18/2026 11:59PM
We are still investigating the issue with our upstream ISP.
Latest Let's Encrypt outages
API Degraded Performance - 16 days ago
Staging: Issuance stopped for incident drill - 3 months ago
Production API Disruption - 6 months ago
High API Latency - 6 months ago
Production API Disruption - 9 months ago
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