Since 2004
Working local, working with https? Got your desktop environment working well, however while using Chrome and browsing you get this "not private" error. You can continue working/browsing if you click through advanced and proceed. This is great but if you are reading this my bet you are looking for a better solution. Read on! - March 24, 2020
Seen1 this "Your connection is not private” while working with https on your localhost (workstation).
In Chrome, put in chrome://flags/#allow-insecure-localhost in the address bar.
Enable the option that says "Allow invalid certificates for resources loaded from localhost".
Restart Chrome, and it should allow the site.
Worked like a charm!