ERR_SSL_UNRECOGNIZED_NAME_ALERT: What It Means

• nginx has no server_name for the requested domain
• Apache is missing a <VirtualHost> with ServerName
• The DNS A record points to an IP where the domain is not configured
• The CDN/reverse proxy does not know the backend domain
• Cloudflare "Full (strict)" without an origin certificate

1. Add server_name example.com www.example.com; to nginx and reload
2. In Apache: <VirtualHost *:443> ServerName example.com ...</VirtualHost>
3. Check DNS — the A record must point to your web server's IP
4. CDN: set the exact Host header in the origin section
5. Cloudflare: install an origin certificate (free in the dashboard)

Check SSL Certificate →

server {
    listen 443 ssl http2;
    server_name example.com;

    ssl_certificate     /etc/letsencrypt/live/example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;

    ssl_protocols       TLSv1.2 TLSv1.3;
    ssl_ciphers         ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256;
    ssl_prefer_server_ciphers off;

    ssl_stapling        on;
    ssl_stapling_verify on;
}

• NET::ERR_CERT_AUTHORITY_INVALID
• ERR_CERT_DATE_INVALID
• ERR_SSL_PROTOCOL_ERROR
• SSL Handshake Failed
• All SSL errors