title: Web app throws ERROR 500 on load, but only if compiled by Maven
body: <p>When I package a Java "dynamic web project" in Eclipse for export, the created WAR can be launched onto a server and the app will load correctly.  </p>
  
  <p>However, if I try and build my project with Maven (w/ and w/o Jenkins), the build will claim it succeeded but the resulting war is messed up somehow because attempting to load my app will give me this error: </p>
  
  <pre><code>**HTTP Status 500 - exception**
  
  org.apache.jasper.JasperException: java.lang.ClassCastException: 
    org.apache.catalina.util.DefaultAnnotationProcessor cannot be cast to org.apache.AnnotationProcessor
  .blah blah blah Stacktrace goes here blah blah....
  
  java.lang.ClassCastException: org.apache.catalina.util.DefaultAnnotationProcessor cannot be cast to org.apache.AnnotationProcessor
  . blah blah blah  Stacktrace goes here blah blah....
  </code></pre>
  
  <p>I've read that this can be caused by a mismatch of Tomcat Versions between what's on the server and what's in my POM, but I've made sure that both are v6.0.26. </p>
  
  <p>Is there something else that could be causing this - something else with my POM, my Maven configuration, or something completely different? </p>