Any website that has HTTPS is not loading properly

Options…

🔸Upgrade to a newer macOS versions, and acquire a hypervisor—Parallels or Fusion or such—and install Yosemite into it, and run your old apps there. This will work on Intel Macs, but you won’t want to try this with Apple silicon Macs.

🔸Upgrade to a newer macOS version, and update or replace your problematic apps. I’d suspect Adobe apps here, and there can be various alternatives, potentially including Affinity Photo.

🔸Stay on the older macOS version, and have increasing difficulties with secure connections and other issues. 10.13 is getting a little dicy here, and you’re much further back. This can include manually adding the LetsEncrypt root certificate. (Info) There will be other issues arising, as connection security that far back has its limits.

🔸Use a different web browser that includes its own certificate chain, at least for as long as those older browsers are still supporting Yosemite.

🔸Transfer the files to your iPhone, and upload from there. There are various apps for various file transfers available in the app store.

In your website HTTPS is not loading properly, there could be several reasons for this issue. And then after showing this error "NET::ERR_CERT_AUTHORITY_INVALID" then it indicates a problem with the SSL/TLS certificate of the website. Follow the few steps to solve this issues.

1) Check your certificate validity

2) Correct your date and time

3) You can try to another browser

4) Check for Intermediate Certificates

5) Update Browser

6) Disable Antivirus or Firewall

7) Check for Man-in-the-Middle Attacks

8) Contact Website Administrator

If the problem will not solved then there's a chance that the SSL certificate on the website is incorrectly configured or has additional problems. In this situation please contact your website's support or technical team is advisable for further assistance.

[Edited by Moderator]