Learn how to fix the TLS Name Mismatch Error in Cloudflare. Our Cloudflare Support team is here to help you with your questions and concerns.

Understanding the TLS Name Mismatch Error in Cloudflare

It is a well-known fact that the TLS ensures secure communication between a client and a server in HTTPS interactions. When a client connects to a website, the server presents an SSL/TLS certificate to verify its identity. The browser checks:

• The certificate must not be expired.
• The certificate must be issued by a trusted Certificate Authority (CA).
• The domain name in the URL must match the certificate’s “Common Name” (CN) or “Subject Alternative Name” (SAN).

If the domain in the URL does not match the domain listed in the certificate, the browser displays a “name mismatch” error. This is flagged as a security risk, often blocking user access until resolved.

Causes of the Cloudflare TLS Name Mismatch Error

1. Cloudflare’s reverse proxy serves the SSL certificate on behalf of our site. If the origin server’s SSL certificate is invalid or does not match the domain, a TLS name mismatch occurs.
2. Cloudflare’s SSL modes (e.g., Flexible, Full, Full (Strict)) require proper configuration. An incorrect or misconfigured certificate can lead to mismatch errors.
3. Using a Subject Alternative Name (SAN) certificate can cause errors if the requested domain is not included in the SAN list.
4. Cloudflare enforces policies that prohibit using a CNAME to point to a domain managed by another Cloudflare account unless authorized. Subdomain misconfigurations can result in a mismatch error.
5. Cloudflare has several SSL/TLS modes, and an incorrect setting can lead to a mismatch.
6. Cloudflare may cache older SSL certificates or configurations, leading to mismatches even after updates.
7. An expired or revoked certificate on Cloudflare or the origin server can cause browsers to display a mismatch error.

How to Resolve Cloudflare TLS Name Mismatch Errors

1. Check Cloudflare SSL Settings

Verify the SSL/TLS configuration in the Cloudflare dashboard to ensure the correct mode is used. Here are the different options:

• Flexible SSL: Use only if the origin server lacks an SSL certificate.
• Full SSL: Use if the origin server has an SSL certificate installed but isn’t fully validated.
• Full (Strict) SSL: Use for the highest security. Both Cloudflare and the origin server must have valid, matching SSL certificates.

We can choose the required mode with these steps:

1. Log in to the Cloudflare dashboard.
2. Go to SSL/TLS settings.
3. Then, select the appropriate SSL mode for our setup.

2. Verify the Certificate on the Origin Server

• Ensure the certificate’s Common Name (CN) or Subject Alternative Name (SAN) matches the domain.
• Confirm the certificate is issued by a trusted CA and is not expired or revoked.

3. Use Cloudflare’s Universal SSL

• Enable Universal SSL in the Cloudflare dashboard under the SSL/TLS section.
• This ensures that Cloudflare provides a valid certificate for your domain.

4. Purge Cloudflare Cache

Cloudflare might cache outdated certificates or responses. Purge the cache to update:

1. Go to the Caching section in the Cloudflare dashboard.
2. Select Purge Everything or purge specific URLs.

5. Check for CNAME Cross-User Issues

• Contact Cloudflare support if the CNAME points to a domain in a different Cloudflare account.
• Adjust DNS settings to authorize the CNAME properly.

6. Re-issue or Renew SSL Certificates

• If the issue concerns an expired or improperly issued certificate, re-issue or renew it.
• Ensure the new certificate includes the correct CN and all SANs for multi-domain setups.

7. Validate DNS and HTTPS Records

• Confirm that DNS records in the Cloudflare dashboard point to the correct origin server.
• Misconfigured CNAME or A records can result in Cloudflare serving the wrong certificate.

Troubleshooting Tools

1. Use tools like SSL Labs’ SSL Test or “What’s My Chain Cert” to analyze SSL certificates and identify mismatch issues.
2. Open Developer Tools (F12 or right-click > Inspect). Then, check the Network tab to view the SSL certificate details served by Cloudflare.
3. Run the following command to inspect the certificate served for a domain:

   openssl s_client -connect www.example.com:443 -servername www.example.com

   This displays the certificate details and helps identify mismatches between the domain and certificate.

[Need assistance with a different issue? Our team is available 24/7.]

Conclusion

Use troubleshooting tools to diagnose and prevent future SSL-related issues, ensuring a secure and seamless user experience.

In brief, our Support Experts demonstrated how to fix the TLS Name Mismatch Error in Cloudflare.