Cloudflare Error 526
Critical
Invalid SSL certificate
The origin certificate could not be validated. This error only occurs when Cloudflare SSL/TLS mode is set to "Full (strict)".
Impact: Website completely inaccessible
Responsibility
Configuration
This error is usually caused by incorrect DNS, SSL, or firewall configurations.
Common Causes
- Origin certificate expired
- Origin uses a self-signed certificate
- Origin certificate hostname mismatch
- Missing intermediate certificate chain
Troubleshooting Guide
1
Update Origin Cert or Downgrade Mode
Recommended: Re-issue a valid certificate on the origin using Let's Encrypt or Cloudflare Origin CA. Workaround: Downgrade SSL mode from "Full (strict)" to "Full".
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