title: JSP throw NullPointException error in the line
body: <p>Today I found JSP throw NullPointException error in the following line  </p>
  
  <pre><code>_el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory()
  </code></pre>
  
  <p>I found delete </p>
  
  <blockquote>
    <p>jsp-api-2.1.jar</p>
  </blockquote>
  
  <p>can fix the issue, but don't know why. Anyone knows the reason for this error.</p>
  
  <p>I am using Tomcat 6.0.33</p>