ERR_SSL_UNRECOGNIZED_NAME_ALERT

• nginx server_name mismatch — cert issued for a different domain
• Cloudflare — domain not in account's zones
• AWS ALB target group without HTTPS listener for this hostname
• Shared hosting (DirectAdmin, cPanel) — wrong vhost routing
• Load balancer SNI-based routing broken

1. nginx: verify server_name matches requested hostname exactly
2. Cloudflare: add DNS record + enable proxy
3. ALB: ensure HTTPS listener has cert bound to hostname
4. Test SNI: openssl s_client -connect ip:443 -servername hostname
5. Enterno SSL for external verify

Check SSL Certificate →

• ERR_SSL_PROTOCOL_ERROR
• NET::ERR_CERT_AUTHORITY_INVALID
• All SSL errors

The ERR_SSL_UNRECOGNIZED_NAME_ALERT error indicates a Server Name Indication (SNI) mismatch during the SSL handshake process. To resolve this issue, ensure that your server's SSL certificate matches the domain being accessed, and verify that the SNI is correctly configured in your server settings. Use commands like openssl s_client -connect example.com:443 -servername example.com to troubleshoot the connection.

The ERR_SSL_UNRECOGNIZED_NAME_ALERT error typically arises when the server cannot recognize the hostname being requested due to a mismatch in the SSL certificate and the requested domain. This issue is largely related to the Server Name Indication (SNI) extension, which allows multiple SSL certificates to be served from a single IP address.

When a client connects to a server using HTTPS, the client sends the requested hostname as part of the SSL handshake. If the server's SSL configuration does not recognize the hostname or if the certificate does not cover the requested domain, the client will receive this error. This can happen for several reasons, including:

• Misconfigured SSL certificate that does not include the requested domain.
• Using an IP address instead of the domain name in the URL.
• Outdated SSL protocols or cipher suites.
• DNS issues leading to incorrect domain resolution.

To diagnose the problem, you can use tools such as openssl or online SSL checkers. The command openssl s_client -connect example.com:443 -servername example.com will help you assess whether the server presents the correct certificate for the specified hostname.

To effectively resolve the ERR_SSL_UNRECOGNIZED_NAME_ALERT error, follow these steps:

1. Verify SSL Certificate Configuration: Ensure that the SSL certificate installed on your server includes the domain name in its Subject Alternative Name (SAN) field. You can check this by using the command:

openssl x509 -in your_certificate.crt -text -noout

1. Check SNI Configuration: Ensure your web server is correctly configured to handle SNI. For example, in Apache, you can set the ServerName and ServerAlias directives in your virtual host configuration:

<VirtualHost *:443>
    ServerName example.com
    ServerAlias www.example.com
    SSLEngine on
    SSLCertificateFile /path/to/certificate.crt
    SSLCertificateKeyFile /path/to/private.key
</VirtualHost>

1. Test with Different Browsers: Sometimes, the error might be browser-specific. Test your website in various browsers to confirm the issue persists across them.

1. Check for DNS Issues: Ensure that the DNS settings point to the correct IP address. Use the nslookup command:

nslookup example.com

1. Update SSL Protocols: Ensure your server supports modern SSL protocols. Disable outdated protocols like SSLv3 and enable TLS 1.2 or higher. You can modify your server configuration accordingly:

SSLProtocol all -SSLv2 -SSLv3

By following these steps, you can effectively troubleshoot and resolve the ERR_SSL_UNRECOGNIZED_NAME_ALERT error, ensuring a secure connection for your users.