title: Xamarin build fails with an unknown error
body: <p>I installed Xamarin and was attempting to compile and run an empty app, but the compilation fails with an unknown error:
  <a href="https://i.stack.imgur.com/zzOeT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/zzOeT.png" alt="Screenshot" /></a></p>
  <p>How can I fix this error?</p>