Root exception is java.rmi.UnmarshalException: failed to unmarshal class weblogi

Found a cause the problem. There was a behavior change in 
ClassLoader.loadClass() handling byte array. As discussed in

http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6434149

Adding this VM argument to client JVM preserves the backward compatible behavior of loadClass() and provides a workaround without patching JDK or WebLogic server:

-Dsun.lang.ClassLoader.allowArraySyntax=true