Apr 30, 2018

How to fix Warning: This page calls for XML namespace declared with prefix [tagname] but no taglibrary exists for that namespace

The problem is caused by XML parser has not been configured to use http://www.w3.org/1999/xhtml as global XML namespace. Add it as shown in the following:

<ui:composition xmlns="http://www.w3.org/1999/xhtml"></ui:composition>