Thread:Project:Support desk/403 Forbidden, when viewing the downloaded file/reply (2)

Your site doesn't seem to be accessible (DNS is not known).

But anyway, check your server's error log. And see Manual:How to debug. First of all you should make sure where the error comes from: from MediaWiki/PHP or from the webserver. The problem is most likely the web server, that has some misconfiguration.

If enabling MediaWiki debug it doesn't generate any MediaWiki debug logs, then the problem is the server configuration.