Cloudflare Strict Mode - 526 Error

Linode Staff

When Utilizing Strict Mode Through Cloudflare, I get the 526 Error. How Can I Fix That?

1 Reply

This could be caused by a number of things. Most common are the following three factors, which I found through my research through Cloudflare's documentation:

  • Unexpired, i.e., the certificate notBeforeDate < now() < notAfterDate
  • Issued by a publicly trusted certificate authority or Cloudflare’s Origin CA
  • Contains a Common Name (CN) or Subject Alternative Name (SAN) that matches the requested hostname

Generally, if your SSL certificate is generated by Cloudflare or Let's Encrypt, the second factor should be taken care of. Also, the first is pretty easy to check with a utility like an SSL Checker:

SSL Checker

The third factor can also be checked there as well. You want to make sure that the Common Name matches the hostname. In my experience, this is a common cause of the 526 error.


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