Problem with application/octet-stream content-type

How to configure that?

the files xxx-yyy-ddd-hhh and xxx-yyy-ddd-hhh.html have the same html
in it.

Typing in the browser is OK.

Typing in the browser get the wronge
content-type application/octet-stream.
A text/html content-type is need.

Posted at Nginx Forum:,248575,248575#msg-248575

Nginx binds file extensions with file types:
An examples there links to

B. R.