Error create Let's Encrypt certificats - Windows Server 2012 + Ngnix - Preliminary validation failed, the server answered '<null>' - Help - Let's Encrypt Community Support
karatejb: [Lets Encrypt] Use win-acme to create or renew the certificate on Windows
Certificate Management using ACME – Versasec
Let's Encrypt - Upgrade Win-Acme Version 1 to Version 2