Users often notice the Cloudflare error "sec_error_unknown_issuer" while accessing websites.

Here at Ibmi Media, as part of our Server Management Services, we regularly help our Customers to resolve related Cloudflare errors.

In this context, we shall look into how to fix this Cloudflare error.

Main Causes of Cloudflare error "sec_error_unknown_issuer" ?

The "sec_error_unknown_issuer" error often triggers due to issues with the SSL certificate. 

Some of the common reasons for this error include:

1. DNS not set as proxied in the Cloudflare panel.

2. Cloudflare nameservers not set for the domains.

3. There are "old" and "cached" certificates at Web browser.

4. Presence of antivirus software.

How to resolve Cloudflare error "sec_error_unknown_issuer" ?

The exact step to be followed to solve the error depends on the exact reasons for this error. Let us now discuss some of the steps to fix this error.

While using Cloudflare SSL for domains, it requires setting the corresponding host to be proxied from the Cloudflare DNS area.

Often turning off the Orange cloud for hostname causes the SSL error. This can be fixed by turning the proxy on.

Further, Cloudflare requires that its nameservers be set for the domain at the domain registrar. Often if we already changed NameServer to the one provided by Cloudflare, we will have to wait until they are propagated.

Also, it is important to ensure that we remove the non-Cloudflare nameservers while adding the Cloudflare one.

Sometimes, you may notice that the error only appears at your end. This happens due to the antivirus installed in the local machine.

At times the anti-virus replaces the certificate and renders it invalid thereby.

Thus disabling it may fix the issue.

Often it could be a mere issue with the browser cache. Thus or engineers ensure both the browser cache and DNS cache are cleared.

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