Index: src/java/org/apache/hadoop/hbase/ipc/HBaseRPC.java =================================================================== --- src/java/org/apache/hadoop/hbase/ipc/HBaseRPC.java (revision 894689) +++ src/java/org/apache/hadoop/hbase/ipc/HBaseRPC.java (working copy) @@ -639,6 +639,10 @@ public Writable call(Writable param, long receivedTime) throws IOException { try { Invocation call = (Invocation)param; + if(call.getMethodName() == null) { + throw new IOException("Could not find requested method, the usual " + + "cause is a version mismatch between client and server."); + } if (verbose) log("Call: " + call); Method method = implementation.getMethod(call.getMethodName(),