In the following simple configuration

server {
server_name testsite.static;
root /some/path/;
index blog.html;
try_files $uri $uri.html =404;
}

the try_files directive seems to interfere with the index directive: I always get 404 for http://testsite.static/. If I remove the fallback part of try_files, the same request results in an error:

*990 rewrite or internal redirection cycle while internal redirect to "/.html.html.html....

The file blog.html is present in /some/path/, so I really do not understand why the file is not found/served for the above URL.