Perhaps it’s because I was still in holiday-mode, but I kept getting a 403 error. Even when I added a `helloworld.html` in the `.well-known` dir. Which was driving me crazy. I even thought it was .net Core 2.x related because all full framework sites were renewing just fine, both MVC and Webform applications.
The answer for my situation was in this comment:
Do you have both http/https binding? http binding is required for it to work.
I did, but I remembered something about forcing to SSL for this website.
I searched my code, but all I could find was commented out:
So how did I manage to force visitors to the SSL version? I could not remember it. There was also no URL rewriting in the web.config. It was a checkbox in IIS which I forgot that I ever changed that setting! (sorry for the Dutch screenshot of IIS 8.5)
It would be nice if the new version of Let’s Encrypt Win Simple would temporary disable it and afterwards restored it.
Here is the link to the latest version 184.108.40.206
Good luck and best wishes for 2018!