HTTP 526 Invalid SSL Certificate: Meaning & How to Fix

Quick answer

HTTP status code 526 (Invalid SSL Certificate) means: Cloudflare cannot validate the SSL certificate on the website's server. Yes, a server error: the website failed to handle the request. Usually only the site owner or host can fix it.

Codes 520–526 are not part of the official HTTP standard; they are returned by Cloudflare's network.

Is it an error?

Cloudflare errors (52x)

Yes, a server error: the website failed to handle the request. Usually only the site owner or host can fix it.

Unofficial codes returned by Cloudflare when it cannot get a valid response from the website's own (origin) server.

Common causes

Expired, self-signed or wrong-hostname SSL certificate

If you are visiting the site

Wait a few minutes before trying again
Contact the website if the problem continues

If you run the website

Install a valid certificate on the server (e.g. Cloudflare Origin CA) and open port 443
Check the SSL/TLS mode: Full (strict) requires a valid, trusted certificate

Frequently asked questions

What does HTTP 526 mean?

HTTP status code 526 (Invalid SSL Certificate) means: Cloudflare cannot validate the SSL certificate on the website's server.

Is HTTP 526 an error?

Yes, a server error: the website failed to handle the request. Usually only the site owner or host can fix it.

How do I fix a 526 error?

If you are visiting the site: Wait a few minutes before trying again; Contact the website if the problem continues. If you run the website: Install a valid certificate on the server (e.g. Cloudflare Origin CA) and open port 443; Check the SSL/TLS mode: Full (strict) requires a valid, trusted certificate.

Cloudflare errors (52x)

HTTP 520 Web Server Returned an Unknown ErrorThe website's server returned an empty, unknown or unexpected response to Cloudflare.HTTP 521 Web Server Is DownThe website's server refused the connection from Cloudflare (the web server is down or blocking Cloudflare).HTTP 522 Connection Timed OutCloudflare timed out while trying to connect to the website's server.HTTP 523 Origin Is UnreachableCloudflare cannot reach the website's server (the origin is unreachable).HTTP 524 A Timeout OccurredCloudflare connected to the website's server, but it did not respond before the timeout (125 seconds by default).HTTP 525 SSL Handshake FailedThe SSL/TLS handshake between Cloudflare and the website's server failed.