The site may be using HTTP, have an invalid/expired certificate, use the wrong hostname, or load insecure content.
Step by Step
- Confirm the address begins with https://.
- Inspect the browser's certificate/connection warning.
- Check certificate expiration and hostname coverage.
- Check whether the page loads HTTP resources inside an HTTPS page.
- Review server/CDN SSL configuration.
If That Doesn't Work
- Do not enter sensitive information into a site with an unexplained certificate warning.
- Changing DNS can expose a certificate mismatch if the new server is not configured for the hostname.