A NoClassDefFound error is slightly different from a ClassNotFound exception; ClassNotFound is where the class mentioned is not in the classpath (which you have apparently solved), but NoClassDefFound means that some dependency of the class you are loading could not be loaded. In this case I would check the documentation of the library you are using and make sure that all needed jar files are in the classpath, not just the one with the class you are calling. In this case, the CoreState class is referencing some class you do not have in your classpath. These can be not trivial to track down, as the JVM does not tell you what class it can't find and the documentation of dependencies is in many cases lacking, but this should at least give you some place to start looking. refer: https://coderanch.com/t/640624/java/NoClassDefFoundError-packages-exists-jar-file