For every Stackexchange and Stackexchange meta site I have tested, HTTPS works as expected.
The exception is this site. When attempting to access this site via HTTPS (https://ux.meta.stackexchange.com/) Firefox delivers this error:
Your connection is not secure
The owner of meta.ux.stackexchange.com has configured their website improperly. To protect your information from being stolen, Firefox has not connected to this website.
Can someone fix it please?