Unable to connect to ACME server

Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. https://crt.sh/?q=example.com), so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.

My domain is: email.notarias183y81.com.mx

I ran this command: win acme v2 ACME server "https://acme-v02.api.letsencrypt.org/"

It produced this output:
No luck yet, attempting to force TLS 1.2...
2025-08-25 08:24:26.454 -06:00 [ERR] Unable to connect to ACME server
System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception.
---> System.Security.Authentication.AuthenticationException: Authentication failed, see inner exception.
---> System.ComponentModel.Win32Exception (0x80090326): Mensaje recibido inesperado, o bien su formato es incorrecto.
My web server is (include version): IIS 8.5

The operating system my web server runs on is (include version): windows server 2012 r2

My hosting provider, if applicable, is:

I can login to a root shell on my machine (yes or no, or I don't know): yes

I'm using a control panel to manage my site (no, or provide the name and version of the control panel):

The version of my client is (e.g. output of certbot --version or certbot-auto --version if you're using Certbot): win- acme v2.10.896

A few months ago Let's Encrypt started using an ECDSA certificate for its API instead of RSA

This is probably causing this problem. See the below thread. It is for a different ACME Client but the changes to Windows are the same.

5 Likes

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.