title: What does "Error in tools:::httpdPort <= 0L : ...." in Rstudio means?
body: <p>I have upgraded R to version 3.2.2.
  When I restart Rstudio, before ">" is shown, there is an error message:</p>
  
  <pre><code>Error in tools:::httpdPort &lt;= 0L :
          comparison (4) is possible only for atomic and list types
  </code></pre>
  
  <p>What does this mean? What should I do to remove this message?</p>