The "XWiki Host" PDF Export configuration parameter has been replaced by a new configuration parameter named "XWiki URI". While the old parameter was used to specify only the domain name or IP address of XWiki (required by the headless Chrome web browser to open the print preview page) the new parameter allows you to specify additionally the scheme (e.g. HTTP versus HTTPS) and the port number (e.g. 8080). This makes it easier to configure the remote Chrome so that it bypasses the proxy (e.g. SSO) in front of XWiki (e.g. by accessing directly the servlet engine that runs XWiki, such as Tomcat).

Note that the old "XWiki Host" configuration parameter is still taken into account (e.g. if it was set before upgrading to XWiki 15.7+) but the new "XWiki URI" parameter takes precedence (when set). We recommend updating your configuration to use the new parameter (in case you're using a remote Chrome and not the user's browser for PDF export). Migration is easy: just copy the value from the old parameter to the new one. This is possible because the scheme and port number are optional when specifying the "XWiki URI".

For more information checkout the PDF Export Application documentation.