title: Cassandra:java.lang.UnsupportedClassVersionError
body: <p>I had no problem with <code>cassandra</code> but today I tried to install the latest cassandra ver ,after installing <code>cassandra</code> when i tried to run this command:</p>
  
  <pre><code>sudo cassandra -f
  </code></pre>
  
  <p>it result in this exception:</p>
  
  <pre><code>Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/cassandra/service/CassandraDaemon : Unsupported major.minor version 51.0
  at java.lang.ClassLoader.defineClass1(Native Method)
  at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
  at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
  at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
  at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
  at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
  at java.security.AccessController.doPrivileged(Native Method)
  at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
  Could not find the main class: org.apache.cassandra.service.CassandraDaemon. Program        will exit.
  </code></pre>
  
  <hr>
  
  <pre><code>java version "1.6.0_27" 
  os:ubuntu 12.04 lts
  </code></pre>