I have a site (Michael’s World) that uses an Azure CDN Endpoint. I have shared here before that you can use this to share static web content. I had it setup with the apex/root domain and went to update the cert. (You have to bring your own cert or pay for a cert for the apex/root).
When I went to renew, I couldn’t get it to work. I kept getting an error:
Failed to update custom domain properties
Sorry, it looks like there was an error on our end. Please contact Support if you keep having this problem.
Turns out, Azure supports "Let’s Encrypt X3". Unfortunately, Let’s Encrypt isn’t using that anymore. They are using “Let’s Encrypt R3” as of December 8th, 2020. Looks like I am out of luck on the apex/root cert until Microsoft updates support.