The ACME server was probably unable to reach - Answer file is correctly rendered.

[brichardson1991]

I've followed all the steps on the wiki: https://github.com/Lone-Coder/letsencrypt-win-simple/wiki/Create-a-SAN-certificate-for-Exchange-2016

When i request my SAN for my 2 hostnames i get the following error:
The ACME server was probably unable to reach "domain"

However when i browse to that particular url in question I can indeed see that i can hit that domain and that challenge file.

Please note i've tried the MVC changes too

[dfarrall]

Can confirm this is also an issue for myself.

[LBegnaud]

are you testing it from an external location? the client is telling the acme server to hit the address, so the request will be coming from the internet.

[brichardson1991]

No i am running it directly on the exchange server and i can hit the acme request url from either on the server itself, or from an external site.

[LBegnaud]

You're giving conflicting information. You responded "no" to say you aren't testing externally, but then you say you are.

If you really are able to download the authorization file using external DNS from outside your exchange server's network, then I'm not sure what the issue is... I can confirm that creating SAN certificates works if the above is satisfied for each SAN fqdn.

[brichardson1991]

Apologies i mis-read what you meant.
i can hit the file it is asking to check when it fails but it doesn't download anything it displays a blank page.
Let me get you a example:
The ACME server was probably unable to reach http://autodiscover.richardson1991.co.uk/.well-known/acme-challenge/wgjAOpKcNeOm1WfkcKAWPMoke0aX0oaBr_G_gK5BPvk

[LBegnaud]

check your filesystem that the file contains data. Perhaps your web.config isn't properly allowing the file to be served? There is info in the wiki about how to allow extension less file handling

[gerard-kanters]

I have the same issue here. Files are there in C:\inetpub\wwwroot.well-known\acme-challenge I can access the files from a browser, both from the server and externally.

[rdebath]

@gerard-kanters If you don't give us the URL we can't help directly.

I would suggest you use something like http://www.infobyip.com/httpservertest.php
It will try to connect to the URL you give and give you the error or a HTTP/1.1 200 OK and the Content-Type: it gets (which must be "text/json")

[gerard-kanters]

Thanks rdebath, it has been resolved. Firewall was not accepting or forwarding http traffic, only https :-)