Hi Amit, I meet this error on the client side when I upgrade 0.92.1 to 0.94. I just put protobuf-java-2.4.9.a.jar into the classpath then the problem sloved.
if you're sure you have protobuf on your CLASSPATH when the job runs, have you just try restart M/R or even Hadoop? I met some strange classNotFound Exceptions when I run mapR before, just restart, and everything may return well.
