title: Mahout 0.8 and hadoop 0.21
body: <p>When I run the mahout command, the following error happens:</p>
  
  <blockquote>
    <p>Running on hadoop, using /usr/local/hadoop/bin/hadoop and
    HADOOP_CONF_DIR= MAHOUT-JOB:
    /home/ubuntu/mahout/examples/target/mahout-examples-0.8-SNAPSHOT-job.jar
    Exception in thread "main" java.lang.NoSuchMethodError:
    org.apache.hadoop.util.ProgramDriver.driver([Ljava/lang/String;)V     at
    org.apache.mahout.driver.MahoutDriver.main(MahoutDriver.java:123)     at
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)   at
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
      at
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:601)     at
    org.apache.hadoop.util.RunJar.main(RunJar.java:192)</p>
  </blockquote>
  
  <p>I have relatively the same problem as here: <a href="https://stackoverflow.com/questions/11751763/mahout-wont-start-up-anything-to-do-with-compatible-version-between-hadoop-and">mahout wont start up. Anything to do with compatible version between hadoop and mahout?</a>
  The difference is that I'm using hadoop 0.21 and mahout 0.8. It is pointed out in the above question that this bug has been fixed in mahout 0.8 but I still encountered the same error.</p>
  
  <p>I found another solution about this problem at <a href="http://comments.gmane.org/gmane.comp.apache.mahout.user/14817" rel="nofollow noreferrer">http://comments.gmane.org/gmane.comp.apache.mahout.user/14817</a> where the author suggested changing the pom.xml file. I tried to change the hadoopverion in the main pom file from 1.1.2 to 0.21.0 but maven repository doesn't have that dependency. Therefore, I changed to 0.20.2 but then mvn compile does not work (mvn compile and mvn install work when I use the hadoop 1.1.2).</p>
  
  <p>Do you have any idea or suggestion ? Thank you.</p>