Browser NET::ERR_CERT_COMMON_NAME_INVALID — SSL Name Mismatch

Overview

NET::ERR_CERT_COMMON_NAME_INVALID means the SSL certificate domain name does not match the website URL you are visiting.

Key Details

• SSL certificates are issued for specific domain names
• The certificate must match the URL domain exactly or via wildcard
• Example: cert for *.example.com does not cover example.com (no subdomain)
• All major browsers show this error, though the code name varies
• Chrome shows 'Your connection is not private' with this error code

Common Causes

• SSL certificate issued for www.example.com but accessed via example.com
• Website using a shared hosting certificate for a different domain
• Certificate SAN (Subject Alternative Name) does not include the accessed domain
• Corporate proxy rewriting HTTPS with its own certificate
• Website recently changed domains without updating the certificate

Steps

1. 1Check if adding or removing 'www.' from the URL fixes it
2. 2Click the padlock > Certificate > check what domain the certificate was issued for
3. 3If you own the site, reissue the certificate to include all needed domains (with and without www)
4. 4Use Let's Encrypt certbot with: certbot --expand -d example.com -d www.example.com
5. 5If a corporate proxy causes this, add the proxy certificate to your browser trust store

Tags

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Frequently Asked Questions