"Your connection is not private"

Also searched as: ssl certificate error · certificate error · connection not secure · net err cert

Updated 9 October 2026

Short answer

Browsers check every HTTPS site's security certificate before showing it. "Your connection is not private" (or NET::ERR_CERT_...) means that check failed: the certificate has expired, was issued for a different domain name, is self-signed, or is missing a piece. Visitors can't safely get past this, so fix it on the server. Clicking the warning and reading the error code tells you which problem it is.

What's the problem

Instead of your site, visitors see a red or grey warning: "Your connection is not private", "Your connection isn't secure", "Warning: Potential Security Risk Ahead", with a code such as NET::ERR_CERT_DATE_INVALID or NET::ERR_CERT_COMMON_NAME_INVALID.

Why it happens

The code after NET::ERR_CERT_ usually says which:

  • DATE_INVALID: the certificate has expired, or the visitor's computer clock is wrong. See SSL certificate expired.
  • COMMON_NAME_INVALID: the certificate is for a different name, for example it covers example.com but not www.example.com.
  • AUTHORITY_INVALID: it's self-signed or from an issuer browsers don't trust, or the server isn't sending the full certificate chain.
  • Only on some networks: an office or public Wi-Fi network intercepting secure traffic.

How to fix it

  1. Click the warning's details and note the error code.
  2. Check the certificate's dates and names. In the browser, click the warning icon in the address bar and view the certificate.
  3. Renew it if expired. Most hosts and Let's Encrypt can renew automatically. Make sure automatic renewal is on and working.
  4. Make sure it covers every name visitors use: with and without www, and any subdomains.
  5. Install the full chain (your certificate plus the issuer's intermediate certificate) if the error is about the authority.
  6. If you use Cloudflare, check the SSL mode matches your server's certificate. "Full (strict)" needs a valid certificate on your server.
  7. If only you see it, check your computer's date and time, and try another network.

What Preventionlabs checks

One click runs the full report on your domain. For this problem it shows whether HTTPS works and http visitors are sent to it; every version of your address (http, https, www) and where each ends up, including redirect loops; insecure http:// files on any of up to 50 pages; your DNS: nameservers, addresses, DNSSEC, and records pointing at services that no longer exist. With Cloudflare connected, it also shows your certificate and the days until it expires; your SSL mode and the other settings that commonly cause this.

Run your free report

Your first report is free, no card needed. Then A$50 a month, up to 10 domains. Read-only: it never changes anything.

Sources

  1. MDN Web Docs: Transport Layer Security (TLS)referenceTo support server authentication, your website must have a digital certificate , which contains a digitally signed copy of the public key which is the counterpart of the website's private key.
  2. MDN Web Docs: Transport Layer Security (TLS)referenceLet's Encrypt is a widely used nonprofit Certification Authority which issues free TLS certificates.

Related

SSL certificate expired Renew the certificate on your server or hosting panel, then fix whatever stopped the automatic renewal so it doesn't happen again in 90 days. HTTPS not working Usually no valid certificate, port 443 closed, or two redirect settings fighting. Check the certificate, then redirects and Cloudflare SSL mode. SSL handshake failed Your server and the browser or Cloudflare couldn't agree on a secure connection: no certificate, wrong SSL mode, or outdated TLS only. Mixed content error Your secure (HTTPS) page loads some files over insecure HTTP. Browsers block them or drop the padlock. Change those links to HTTPS.
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