title: Java and NetBeans E-commerce Tutorial: project fails to run on Snapshot 8
body: <p>I am studying Java through the <a href="https://netbeans.org/kb/docs/javaee/ecommerce/intro.html" rel="nofollow">NetBeans E-commerce tutorial</a>. It's a bit out of date, but I've been able to work around the deprecations while using NetBeans IDE v8.1 and Glassfish 4.1.1 (the tutorial uses NetBeans 6/7 and Glassfish 3.x.x). </p>
  
  <p>However, on Step 9, "Integrating Business Transaction Logic", my build suddenly started failing after the sub-section Setting up the Transaction Programmatically. Both my own work and the <a href="https://netbeans.org/projects/samples/downloads/download/Samples%252FJavaEE%252Fecommerce%252FAffableBean_snapshot8.zip" rel="nofollow">official SnapShot 8</a> throw the same error.</p>
  
  <pre><code>Severe:   Exception while loading the app : java.lang.IllegalStateException: 
  ContainerBase.addChild: start: org.apache.catalina.LifecycleException: 
  org.apache.catalina.LifecycleException: java.lang.IllegalArgumentException: 
  Can not set session.CategoryFacade field 
  controller.ControllerServlet.categoryFacade to controller.ControllerServlet
  </code></pre>
  
  <p>I've examined all the files referred to in this error, but I'm not finding any syntax errors or anything else obviously wrong.</p>
  
  <p>Can anyone explain what this error means and how to resolve it?</p>