title: Tomcat after undeploy/deploy a war makes NoClassDefFoundError: org.apache.xml.serializer.TreeWalker
body: <p>After deploying the same war which was perfectly OK before the deploy. I got this exception:</p>
  
  <pre><code>java.lang.NoClassDefFoundError: org/apache/xml/serializer/utils/DOM2Helper
          at org.apache.xml.serializer.TreeWalker.&lt;init&gt;(TreeWalker.java:121)
  </code></pre>
  
  <p>It is the part of <strong>serializer-2.7.1.jar</strong> and managed by maven.</p>
  
  <p>It seems somehow the undeploy/deploy proccess screw the libs. Any idea how to get rid of this exception? Now the workaround just to restart the server after every deploy, but it is not nice. Maybe i should add the lib to tomcat lib, or new JRE/JDK can do the job?</p>
  
  <p><strong>Update:</strong>
  tomcat/lib:</p>
  
  <pre><code>annotations-api.jar  catalina-storeconfig.jar  ecj-P20140317-1600.jar  jasper.jar       tomcat-api.jar     tomcat-i18n-es.jar  tomcat-jdbc.jar  tomcat-util-scan.jar  websocket-api.jar
  catalina-ant.jar     catalina-tribes.jar       el-api.jar              jsp-api.jar      tomcat-coyote.jar  tomcat-i18n-fr.jar  tomcat-jni.jar   tomcat-util.jar
  catalina-ha.jar      catalina.jar              jasper-el.jar           servlet-api.jar  tomcat-dbcp.jar    tomcat-i18n-ja.jar  tomcat-spdy.jar  tomcat-websocket.jar
  </code></pre>
  
  <p>Anyone has experience with this problem?</p>