CHECK GLOSSARY · TLS-001

Certificate problem or near expiry

In plain words: An invalid or expired certificate makes browsers block the site with a warning page.

How to fix it

Renew the certificate and enable auto-renewal.

Official sources

• Let's Encrypt: integration guide

Related checks

• HTTPS-002: http does not redirect to https
• HSTS-001: No HSTS header
• TLS-002: Outdated TLS version
• HTTP2-001: HTTP/2 not enabled

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