ERR_CERT_COMMON_NAME_INVALID

Plain-English meaning

TLS certificate does not match hostname in URL.

Why it happens

Certificate SAN/CN does not include requested domain or wrong cert served for SNI.

Common causes

  • Certificate issued for different domain
  • Wildcard does not cover nested hostname
  • CDN/origin serves default certificate
  • Stale certificate after renewal

What to check first

Inspect SAN list via browser/openssl, verify DNS destination, and confirm SNI-specific cert mapping.

How to fix it

Install correct cert chain for hostname, update SAN coverage, and automate renewal deployment checks.

Example signal

net::ERR_CERT_COMMON_NAME_INVALID
requested host: app.example.com

Related links

404 · 429 · 500 · 502 · 503 · 504 · Cloudflare 522 · Nginx 499 · ERR_CONNECTION_REFUSED

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