Not able to start the remote server - class not found exception

Question

All,
I am quite new to RMI programming, although i am an experienced java programmer. I am facing a problem in starting the remote server program which i wrote for RMI. I am getting class not found exception for "stub" class eventhough the class is in the classpath.
Following is the error console:
cmd> java -classpath "D:\Eclipse_WorkSpaces\WS2\RMITests\classes" MyServerImplementation
GetNames error: RemoteException occurred in server thread; nested exception is:
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: MyServerImplementation_Stub
java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: MyServerImplementation_Stub
at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:396)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:250)
at sun.rmi.transport.Transport$1.run(Transport.java:159)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:155)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:535)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:790)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:649)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:255)
at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:233)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:359)
at sun.rmi.registry.RegistryImpl_Stub.rebind(Unknown Source)
at java.rmi.Naming.rebind(Naming.java:160)
at MyServerImplementation.main(MyServerImplementation.java:21)
Caused by: java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: MyServerImplementation_Stub
at sun.rmi.registry.RegistryImpl_Skel.dispatch(Unknown Source)
at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:386)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:250)
at sun.rmi.transport.Transport$1.run(Transport.java:159)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:155)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:535)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:790)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:649)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.ClassNotFoundException: MyServerImplementation_Stub
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:247)
at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:434)
at sun.rmi.server.LoaderHandler.loadClass(LoaderHandler.java:165)
at java.rmi.server.RMIClassLoader$2.loadClass(RMIClassLoader.java:620)
at java.rmi.server.RMIClassLoader.loadClass(RMIClassLoader.java:247)
at sun.rmi.server.MarshalInputStream.resolveClass(MarshalInputStream.java:197)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1575)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1496)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1732)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351)
... 12 morePLEASE ADVISE HOW TO RESOLVE THIS...
Following are my classes:
MyRemoteInterface.java
import java.rmi.Remote;
import java.rmi.RemoteException;
public interface MyRemoteInterface extends Remote {
public String[] getNames() throws RemoteException;
public class MyServerImplementation extends UnicastRemoteObject implements
MyRemoteInterface {
public MyServerImplementation()throws RemoteException{
super();
public String[] getNames() throws RemoteException{
return new String[]{"Name1","Name2","Name3","Name4"};
public static void main(String args[]) {
try {
// Create an object of the HelloWorldServer class.
MyRemoteInterface obj = new MyServerImplementation();
// Bind this object instance to the name "HelloServer".
Naming.rebind("rmi://localhost:1985/GetNames", obj);
System.out.println("GetNames bound in registry");
catch (Exception e) {
System.out.println("GetNames error: " + e.getMessage());
e.printStackTrace();
public class MyRMIClient {
*@param args*
public static void main(String[] args) {
try {
MyRemoteInterface remObj = (MyRemoteInterface) Naming.lookup("rmi://localhost:1985/GetNames");
System.out.println("Names are "+remObj.getNames());
catch(Exception e) {
System.out.println("Problem encountered accessing remote object "+e);
}

Answer 1

That's a remote exception coming from the registry. You need to learn to recognize remote exceptions and their source, it's a mjaor source of confusion in RMI.
In this case it's the registry that can't find the stub class.
The stub class needs to be in the CLASSPATH of (i) the Registry and (ii) the client as well. Ditto the remote interface; ditto any application classes it refers to, and so on until closure.
The easiest way to achieve (i) is to start it in the server's JVM, with LocateRegistry.createRegistry().