We'll create fresh WordPress site with Force text/xml as MIME-type in the feed installed. You have 20 minutes to test the plugin after that site we'll be deleted.
In the last versions of WordPress the feed can be generated as application/rss+xml, application/rss+xml, text/xml, application/atom+xml’ or application/rdf+xml
Some of these content-types are not recognized by old feed readers or some JAVA feed managers (as Jsoup) generating a validation exception.
This plugin overwrite the content-type by ‘text/xml’ used in the past.