This is a typical RMI stubs-related error:

java.rmi.StubNotFoundException: 
         Stub class not found: rmi.FileClassifierImpl_Stub; 
nested exception is: 
        java.lang.ClassNotFoundException: rmi.FileClassifierImpl_Stub

This error does not occur as frequently as it used to. From Jini 2.0 onwards proxies should be generated using Jeri instead of RMI and this error will only occur when using RMI. If it does occur, then the best thing to do is to change the application to use Jeri. See chapter 10 for this.