Hi

We are having this exact problem as well. I can see that the issue is with the letsencrypt client as running it manually gives us the same error. The error is

Exception "Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information."

This error has been logged on GitHub already here  https://github.com/Lone-Coder/letsencrypt-win-simple/issues/648

Just to be sure, we are going to patch the server with all available windows updates as we have a few outstanding and then try again.  If that works I will let you know.

Mark Donne
HOST100

I get the same error:

Exception “Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.”

Did you get it fixed?