Why Chrome says a site is not secure

Chrome's “Not secure” warning can identify an HTTP page, a certificate problem, or mixed content. Inspect the address bar and certificate details before bypassing anything.

If the site is yours, check that:

• the URL uses HTTPS and the certificate covers the exact hostname;
• the certificate is current and its chain is served correctly;
• the server's clock and redirect configuration are correct;
• page resources use HTTPS, so scripts/images are not mixed content;
• the reverse proxy forwards the original scheme correctly.

A private or self-signed certificate may be appropriate for a controlled development network but should not be presented as public trust. On a public site, use a certificate authority and renew it before expiry. If only one device sees the warning, check its clock, proxy, antivirus HTTPS inspection, and trust store.

Do not enter passwords or payment data after dismissing a certificate warning. For a site you do not control, report the exact URL to its owner; the browser warning is not evidence that the site's content is malicious, but it is a reason to treat the connection cautiously.

Sources

• Chrome Help — connection security

• MDN — HTTPS