title: hadoop Protocol message tag had invalid wire type
body: <p>I Set up hadoop 2.6 cluster using two nodes of 8 cores each on Ubuntu 12.04. <code>sbin/start-dfs.sh</code> and <code>sbin/start-yarn.sh</code> both succeed. And I can see the following after <code>jps</code> on the master node. </p>
  
  <pre><code>22437 DataNode
  22988 ResourceManager
  24668 Jps
  22748 SecondaryNameNode
  23244 NodeManager
  </code></pre>
  
  <p>The <code>jps</code> outcome on the slave node is </p>
  
  <pre><code>19693 DataNode
  19966 NodeManager
  </code></pre>
  
  <p>I then run the PI example. </p>
  
  <p><code>bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.6.0.jar pi 30 100</code></p>
  
  <p>Which gives me there error-log</p>
  
  <pre><code>java.io.IOException: Failed on local exception: com.google.protobuf.InvalidProtocolBufferException: Protocol message tag had invalid wire type.; Host Details : local host is: "Master-R5-Node/xxx.ww.y.zz"; destination host is: "Master-R5-Node":54310; 
      at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:772)
      at org.apache.hadoop.ipc.Client.call(Client.java:1472)
      at org.apache.hadoop.ipc.Client.call(Client.java:1399)
      at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:232)
      at com.sun.proxy.$Proxy9.getFileInfo(Unknown Source)
      at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getFileInfo(ClientNamenodeProtocolTranslatorPB.java:752)
  </code></pre>
  
  <p>The problem seems with the HDFS file system since trying out the command <code>bin/hdfs dfs -mkdir /user</code> fails with the similar exception. </p>
  
  <pre><code>java.io.IOException: Failed on local exception: com.google.protobuf.InvalidProtocolBufferException: Protocol message tag had invalid wire type.; Host Details : local host is: "Master-R5-Node/xxx.ww.y.zz"; destination host is: "Master-R5-Node":54310;
  </code></pre>
  
  <p>where <code>xxx.ww.y.zz</code> is the ip-address of Master-R5-Node</p>
  
  <p>I have checked and followed all the recommendations of <a href="http://wiki.apache.org/hadoop/ConnectionRefused" rel="nofollow">ConnectionRefused</a> on Apache and on this site. </p>
  
  <p>Despite the week long effort, I cannot get it fixed. </p>
  
  <p>Thanks. </p>