No, unfortunately I didn't manage it and now got the certificate elsewhere.
But of course I want it to work next time.
So here are a few more questions.
Are the following settings correct, or must nsAccept be used here?
Do I have to manually create the /.well-known/acme-challenge/ directory or another one below ROOT or is another directory expected or created automatically?
Can I use my own THandler for ACME HTTP requests on port 80 so that I don't have to open the server for HTTP requests in general?
THandlers::Add(L"/.well-known/acme-challenge/", L"", new TIWH_Acme(PathAcmeChallenge));
the error disappeared by itself in a later intraweb version, but now I'm using IW15.2.64.
Unfortunately, I still couldn't get the intraweb certificate manager to work with Let's Encrypt.
Since I didn't get an answer and there is no example either, I created an ACME handler and tried it with another certificate manager and it worked!
I went back to the version of IW I used in July, the last time getting a LE certificate worked. This was IW15.2.55
Even with that version running, the LE error is the same. The version of IW used does not make a difference in my case.
IW15.2.55 15.2.60 and IW15.2.65
I think you're right, it wasn't directly because of Intraweb.
I was trying to track down the error and it was probably an exception in Indy.
But I can no longer understand it because I had to reinstall my PC for another reason.