Browser security errors › Firefox
SEC_ERROR_UNKNOWN_ISSUER: how to fix it on your website
Firefox cannot build a chain from your certificate to a root it trusts.
What your visitors see
'Warning: Potential Security Risk Ahead'. Chrome may still work because it can fetch missing intermediates.
Common causes
- Missing intermediate certificate
- Self-signed certificate
- HTTPS inspection software on the visitor's machine
How to fix it
- Serve the full certificate chain
- Use a public CA certificate
- Retest in Firefox after reloading the server
Check your certificate and TLS setup
Korrali Web scans your site for certificate, TLS and security header problems and can monitor it so you hear about expiry before visitors do.