title: Openstack instance status is "error"
body: <p>I create a instance in horizon. But its status is "error". Then I run </p>
  
  <pre><code>virsh list --all
  </code></pre>
  
  <p>There is nothing. I have checked log files, including nova/api.log, nova/compute.log, and I can not find any clues. Could someone give some advice ?</p>