So, I'm visiting a random site, and Chrome reports it as "not secure," even though it's using https with a valid certificate. Just as a matter of self-education, I want to understand what they're doing wrong. What things do I need to read about? What kind of tools should I learn how to use.

This is Stack Exchange, so you should make your answer as general as you can.

closed as too broad by dan Sep 25 '18 at 2:33

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • Questions here are required to be about a website under your own control. Additionally, this is really too broad since there could be many potential issues that result in this. The answer below however is one of the more common reasons we see here. – dan Sep 25 '18 at 2:34
  • Chrome is certainly telling you more than just "not secure" .... – Patrick Mevzek Sep 25 '18 at 14:42
  • I think the "site not under your control" rule doesn't apply, since the question isn't about the site. But if you consider this too broad a question, by all means close it. – Isaac Rabinovitch Sep 25 '18 at 20:03

I'm using Chrome so, when I click the SSL certificate information button, I see the following:

Your connection to this site is not fully secure

This indicates that the site is serving some contents over a TLS connection, but other contents are being served over HTTP (unencrypted).

There's nothing wrong with this site's SSL certificate (at least, not anything conspicuous) but, when you encounter a certificate warning like a "This site is not safe" browser warning, you can diagnose the issue with Qualsys' SSL Checker (or another online SSL checker of your choosing - Google "ssl certificate analysis" for a handful of options).

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