title: hcitool lescan Set scan parameters failed: Input/output error
body: <p>the following command </p>
  
  <pre><code>sudo hcitool lescan
  </code></pre>
  
  <p>throws the following error:</p>
  
  <pre><code>Set scan parameters failed: Input/output error
  </code></pre>
  
  <p>I have tried</p>
  
  <pre><code>hciconfig hci0 down
  hciconfig hci0 up
  </code></pre>
  
  <p>and then </p>
  
  <pre><code>service bluetooth restart
  service dbus restart
  </code></pre>
  
  <p>and tried againg. still didnt work.</p>
  
  <p>OS: Ubuntu 18.04
  bluez version: 5.48</p>