Failed to load or instantiate TagLibraryValidator class

running the springMVC-petclinic-hibernate sample app,
got this:
SEVERE: Exception Processing ErrorPage[exceptionType=java.lang.Exception, location=/WEB-INF/jsp/uncaughtException.jsp]
org.apache.jasper.JasperException: /WEB-INF/jsp/uncaughtException.jsp(1,1) Failed to load or instantiate TagLibraryValidator class: org.apache.taglibs.standard.tlv.JstlCoreTLV
        at org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:40)

solution: create a folder springMVC-petclinic-hibernate\web\WEB-INF\lib, then put jstl.jar and standard.jar inside it.
reason: even though the jstl.jar is already in classpath, it’s ignored by the servlet container; have to put the jar along with jsp pages manually.