JSTL: core:redirect gives the error “Unknown tag”


You need to install and declare the taglib before you can use its tags.
  1. Download jstl-1.2.jar and place it in /WEB-INF/lib or /appserver/lib if not done yet.
  2. Declare <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> in top of your JSP.
  3. Now you can use <c:redirect />.