Splitview controller is expected to have a view controller at index 0 before it's used!

I am trying to create a Master/Detail page and I get this error:

Splitview controller is expected to have a view controller at index 0 before it's used!

Anyone have any idea what it means or what to do about it?

This is my xaml:

<?xml version="1.0" encoding="utf-8"?>
<MasterDetailPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="MasterDetail.MDPage">
  <MasterDetailPage.Master>
    <ContentPage Title="title1">
        <Label Text="Master"/>
    </ContentPage>
  </MasterDetailPage.Master>
  <MasterDetailPage.Detail>
    <ContentPage>
        <Label Text="Details"/>
    </ContentPage>
  </MasterDetailPage.Detail>
</MasterDetailPage>