According to TLD or attribute directive I...

It may be because the JSP2.0 version is used, and the standby version of The JSTL core library (RT Library) is not used. There are two solutions:

1. modify web. xml.

<Web-app xmlns = "http://java.sun.com/xml/ns/j2ee" xmlns: xsi = "http://www.w3.org/2001/XMLSchema-instance" xsi: schemaLocation = "http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version = "2.4">
Changed to Version 2.3

<! DOCTYPE web-app PUBLIC "-// Sun Microsystems, Inc. // DTD Web Application 2.3 //" http://java.sun.com/dtd/web-app_2_3.dtd ">
<Web-app>
2. Use the JSTL core RT Library

The JSTL core library has two types of taglib pseudocommands. The RT library relies on the traditional JSP request-time attribute value instead of EL for implementation (called EL library. JSP2.0 will support EL) www.2cto.com

JSP using <% @ taglib uri = http://java.sun.com/jstl/core prefix = "c" %> in Version 2.3 can be, in version 2.4 will not work, is it version incompatible?

As long

<% @ Taglib uri = "http://java.sun.com/jstl/core" prefix = "c" %>
Change

<% @ Taglib uri = http://java.sun.com/jstl/core_rt prefix = "c" %>
Author: Yushizi