I found this topic with similar issue, but no solution there:
Issue - pki-validation folder returns 404 on new server
In my case files in /.well-known are available, while /.well-known/acme-challenge/ is not.
Hi!
I have an iisue with AutoSSL certificate renewal. Reading of manuals showed that files from https://mydomain.com/.well-known/acme-challenge/ folder should be accessible. So I've created test.txt file and trying to access it using this URL...