title: Proguard error: "Exception while processing task java.io.IOException: Please correct the above warnings first"
body: <p>Since upgrading to android gradle plugin 3.0.1 I am getting following error:</p>
  
  <pre><code>Warning: Exception while processing task java.io.IOException: Please correct the above warnings first.
  </code></pre>
  
  <p>:app:transformClassesAndResourcesWithProguardForProductionRelease FAILED</p>
  
  <p>Problem is: I don't see any warning in my log. </p>
  
  <p>I also ran the build with -i flag and I am getting following (big) log:
  <a href="https://gist.github.com/stoefln/b5e5e899c73b52d8065a5daeead716b3" rel="noreferrer">https://gist.github.com/stoefln/b5e5e899c73b52d8065a5daeead716b3</a></p>
  
  <p>Any ideas are very welcome!</p>