526 Invalid SSL Certificate
A Cloudflare error meaning the origin's SSL certificate could not be validated.
What it means
HTTP 526 is a non-standard Cloudflare status returned when Cloudflare cannot validate the SSL certificate presented by the origin server while using a strict SSL mode. The handshake itself may proceed, but the certificate fails validation — it is expired, self-signed, or untrusted — so Cloudflare refuses the connection.
When it happens
It happens under Cloudflare's Full (Strict) SSL mode when the origin serves an expired, self-signed, or otherwise untrusted certificate, or one whose hostname does not match.
How to fix it
- Install a valid certificate from a trusted authority on the origin, or use a Cloudflare Origin CA certificate.
- Renew an expired origin certificate.
- If a self-signed certificate is intentional, switch Cloudflare to Full instead of Full (Strict).
- Make sure the certificate's hostname matches the origin it is serving.
SEO impact
Damaging if sustained. While the certificate fails validation, crawlers receive a server error and the page stays out of the index until the origin certificate is fixed.
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Related codes
A generic error meaning the server encountered an unexpected condition.
501 Not ImplementedThe server does not support the functionality required to fulfil the request.
502 Bad GatewayA server acting as a gateway received an invalid response from the upstream server.
503 Service UnavailableThe server is temporarily unable to handle the request, often due to overload or maintenance.
504 Gateway TimeoutA gateway server did not receive a timely response from the upstream server.
505 HTTP Version Not SupportedThe server does not support the HTTP protocol version used in the request.
Related guides
A plain-English primer on HTTP status codes for SEOs: what the 2xx, 3xx, 4xx, and 5xx families mean, which ones affect rankings, and the codes worth knowing.
How to find and fix broken linksA practical walkthrough for finding broken links on your site, working out why each one breaks, and fixing them so visitors and crawlers stop hitting dead ends.