The file /etc/xwiki/jetty-ee8-web.xml is missing.
The workaround is to download it from https://raw.githubusercontent.com/xwiki/xwiki-platform/master/xwiki-platform-core/xwiki-platform-web/xwiki-platform-web-war/src/main/webapp/WEB-INF/jetty-ee8-web.xml.
