title: cqlsh connection error: 'ref() does not take keyword arguments'
body: <p>I've tried all the measures from <a href="https://stackoverflow.com/questions/29121904/cassandra-cqlsh-connection-refused">this post</a> and <a href="http://wiki.apache.org/cassandra/GettingStarted" rel="noreferrer">Cassandra doc</a>. </p>
  
  <p>I've tried running all the versions of Cassandra including the latest release 3.7 from tarball and Debian package, but I keep getting errors when I execute <code>cqlsh</code>.</p>
  
  <p>Error:</p>
  
  <blockquote>
    <p>Connection error: ('Unable to connect to any servers', {'127.0.0.1': TypeError('ref() does not take keyword arguments',)})</p>
  </blockquote>
  
  <p>I had no problem running Cassandra before I upgraded my Linux Mint from 17.3 to 18.</p>
  
  <p>I believe I installed all the necessary packages such as java 8 and python 2.7.12.</p>
  
  <p>I think the problem exists in cassandra.yaml file since the default setting isn't working, but I'm not sure how to configure properly to get it running.</p>
  
  <p>Any suggestions appreciated.</p>