title: Upgrading the quartz from 1.5.2 to 2.2.0 on JBoss 4.2.2 GA
body: <p>After trying around following Kariem's comments(showing how to upgrading from 1.5.2 to 1.6.0), I am also trying to upgrade Quartz Scheduler 1.5.2 to 2.2.0. The java version on the server is 1.6.</p>
  
  <p>However, when I execute the scheduler after rebooting the server, it shows me the error below. I tried to change it back to 1.5.2. The error message is the same still. Does anyone know how to fix it?</p>
  
  <p>17:13:58,811 ERROR [STDERR] Exception in thread "Thread-11" <br>
  17:13:58,813 ERROR [STDERR] java.lang.IncompatibleClassChangeError: Implementing class <br>
  17:13:58,814 ERROR [STDERR]     at java.lang.ClassLoader.defineClass1(Native Method) <br>
  17:13:58,814 ERROR [STDERR]     at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632) <br>
  17:13:58,814 ERROR [STDERR]     at java.lang.ClassLoader.defineClass(ClassLoader.java:616) <br>
  17:13:58,814 ERROR [STDERR]     at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141) <br>
  17:13:58,814 ERROR [STDERR]     at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1814) <br>
  17:13:58,814 ERROR [STDERR]     at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:872) <br>
  17:13:58,814 ERROR [STDERR]     at org.jboss.web.tomcat.service.WebAppClassLoader.findClass(WebAppClassLoader.java:139) <br>
  17:13:58,814 ERROR [STDERR]     at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1325) <br>
  17:13:58,814 ERROR [STDERR]     at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1204)</p>