News Sitemap Error

Hi @giellemme are you seeing any related errors in the Varnish, Nginx or PHP error logs?

If you switch the “Sitemap Server” option on Settings > XML Sitemap from “WordPress Core” to “Plugin” does the regular sitemap also show this error then?

Note: I notice that your /robots.txt is not responding. You might need to verify your Nginx server block. I find that the General rules on https://developer.www.ads-software.com/advanced-administration/server/web-server/nginx/ work best.