NET::ERR_CERT_COMMON_NAME_INVALID on root domain wellnessidea.co.kr

[gywjd2701]

What is the name of the domain?

wellnessidea co kr

What is the error number?

NET::ERR_CERT_COMMON_NAME_INVALID

What is the error message?

Your connection is not private NET::ERR_CERT_COMMON_NAME_INVALID

What is the issue you’re encountering

Universal SSL is active on Cloudflare, and https://www.wellnessidea.co.kr works correctly. However, accessing https://wellnessidea.co.kr (non-www root domain) returns a certificate mismatch error: NET::ERR_CERT_COMMON_NAME_INVALID. I suspect the root domain is not included in the edge certificate.

What steps have you taken to resolve the issue?

• Waited 12+ hours after Universal SSL activation
• Set Page Rules to redirect root to www
• Confirmed nameservers and DNS records (A + CNAME) are correctly set
• SSL/TLS mode set to Full
• Verified certificate is shown as “Active”
• Tried purging cache / switching Flexible ↔ Full
• Verified proxy (orange cloud) is ON

Was the site working with SSL prior to adding it to Cloudflare?

No

What is the current SSL/TLS setting?

Full

What are the steps to reproduce the issue?

1. Open a browser (Chrome, Safari, etc.)
2. Go to https://wellnessidea.co.kr (non-www)
3. SSL warning appears: “Your connection is not private”
4. Browser displays NET::ERR_CERT_COMMON_NAME_INVALID

Screenshot of the error

[sjr]

Neither your apex domain nor www are using the Cloudflare proxy at the moment…
https://cf.sjr.dev/tools/check?c7a7b04e54a6434e93d6d80a3d1f8b23#dns

…so any certificate issues are on your origin where the certificate returned for your apex domain isn’t for your domain…

* Server certificate:
*  subject: CN=blog.nare.me
*  start date: Apr  9 22:45:04 2025 GMT
*  expire date: Jul  8 22:45:03 2025 GMT
*  issuer: C=US; O=Let's Encrypt; CN=R11
*  SSL certificate verify ok.