HTTP 526 (Invalid Certificate): meaning and handling

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: HTTP 526 is a Cloudflare response indicating that the origin TLS certificate could not be validated in strict mode.

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HTTP_STATUS_HANDSHAKE_FAILED	HTTP_STATUS_RAILGUN_ERROR

HTTP_STATUS_INVALID_CERTIFICATE

Cloudflare documents 526 when Full (strict) mode is enabled and the origin certificate cannot be validated. The certificate can be expired, mismatched, missing an intermediate, or otherwise unsuitable for the origin hostname.

Inspect the certificate chain served by the origin for the requested SNI name, including every backend node. Fix the certificate or hostname configuration rather than lowering verification merely to suppress the error.

A 526 is associated with strict certificate validation on the Cloudflare-to-origin TLS leg. Check that the origin presents a currently valid certificate for the requested hostname and a chain Cloudflare can validate. Replacing the browser certificate or clearing browser state does not address this origin-side certificate validation failure.

Cloudflare: Error 526

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