title: ADB logcat fails to clear the main log
body: <p>When I connect to a device or an emulator using adb, I can clear logcat using <code>adb logcat -c</code>. The issue I am facing is that I often get the following message:</p>
  
  <pre><code>failed to clear the 'main' log
  </code></pre>
  
  <p>AFAIK, 'main' is a non-rooted buffer which means that I should be able to clear it without root. What can then be the reason for this message?</p>