HTTP 526 Invalid SSL Certificate

What does HTTP 526 mean?

Cloudflare could not validate the SSL certificate on the origin. Happens in “Full (strict)” mode when the origin’s certificate is expired, self-signed, issued for another hostname or missing intermediate certificates.

5xx Server error: The request looked valid, but the server failed to fulfil it. The fix is on the server side.

Common causes of a 526 error

• Expired origin certificate.
• Self-signed certificate while using “Full (strict)”.
• Certificate issued for a different hostname.

How to fix 526 Invalid SSL Certificate

• Renew the certificate, or install a Cloudflare Origin CA certificate.
• Make sure the certificate covers the exact hostname, including www.
• Inspect the chain with the SSL certificate decoder.

526 and SEO

Visitors and crawlers get an error page; fix it quickly.

Example response

HTTP/1.1 526 Invalid SSL Certificate

Related status codes

• 525 SSL Handshake Failed — Cloudflare could not complete a TLS handshake with the origin.
• 520 Web Server Returned an Unknown Error — Cloudflare received an empty, unknown or unexpected response from the origin server.

Check which status code a URL returns with the HTTP header checker.