If this error appears AFTER you click on the "Login"/"Registration" buttons BEFORE you enter your password, you need to contact [email protected] with your external IP address (you can check it at 2ip.io, preferably send a full-screen screenshot of a page), a description of the situation and a full-screen screenshot of the error.
If an error occurs AFTER entering the login and password when clicking on the login confirmation button, then you need to check the address bar, there should be an "https://" in front of the site address. If the address bar is "http://", you must manually register the "s" letter.