Eclipse jstl errors

The error message: 

Can not find the tag library descriptor for “http://java.sun.com/jsp/jstl/core”

 Overview: 

JSTL (JSP Standard Tag Library) is a JSP based standard tag library which offers tags usefull for page creation.
The jstl/core resides in jstl jar package. Till version 1.0 it was placed inside the main directory and definition to it was:
<%@taglib uri="http://java.sun.com/jstl/core" prefix="c"%>

 From version 1.1 the correct definition is:
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

Solution: 

In the project preferences check the Target servers settings. When those settings are ok, try to remove and add one more time the server.

more details:
http://stackoverflow.com/tags/jstl/info