title: java.lang.LinkageError: loader constraint violation: when resolving interface method  javax.servlet.jsp.JspApplicationContext.getExpressionFactory()
body: <p>I am using JSF 2.0 in Eclipse IDE. When I tried to implement JSP and Servlet, I get the following error:</p>
  
  <pre><code>java.lang.LinkageError: loader constraint violation: when resolving interface
       method  "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()
       Ljavax/el/ExpressionFactory;" the class loader (instance of 
       org/apache/jasper/servlet/JasperLoader) of the current class,      
       org/apache/jsp/exCrop_jsp, and the class loader (instance of  
       org/apache/catalina/loader/StandardClassLoader) for resolved class, 
       javax/servlet/jsp/JspApplicationContext, have different
       Class objects for the type javax/el/ExpressionFactory used in the signature
  at org.apache.jsp.exCrop_jsp._jspInit(exCrop_jsp.java:31)
  at org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:49)
  at org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:181)
  at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370)
  at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:389)
  at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
  </code></pre>
  
  <p>How is this caused and how can I solve it?</p>