A TLS certificate helps a browser verify a website's identity and establish an encrypted HTTPS connection. Certificates have validity dates and must be renewed before they expire.
Why it matters
An expired or invalid certificate can trigger browser warnings and prevent visitors from trusting the HTTPS connection. A currently valid certificate does not guarantee that every aspect of a website is secure.
How to investigate
- Use the report evidence to identify the hostname and observed certificate dates, if provided.
- Inspect the certificate in a browser or your hosting/certificate provider dashboard.
- Confirm it covers the exact hostname visitors use, including relevant subdomains.
- Check that automatic renewal is enabled and validation settings have not changed.
- Renew or reinstall the certificate using your host's documented process.
- Test HTTPS again and verify the new dates and certificate chain.
If the report shows an expiry warning
Confirm the finding promptly, especially if expiry is near. Redirects, CDNs, multiple hostnames, or temporary network conditions can affect automated checks, so verify the certificate for the exact hostname.
Never advise visitors to bypass certificate warnings or enter sensitive information through a connection they cannot verify. If you do not manage the site, contact its owner or host.