xamarin Android.Content.Res.Resources+NotFoundException: '无法找到资源 ID #0xffffffff'

如何解决xamarin Android.Content.Res.Resources+NotFoundException: '无法找到资源 ID #0xffffffff'

错误：

xamarin Android.Content.Res.Resources+NotFoundException: 'Unable to find resource ID #0xffffffff'

错误在行 auth = DependencyService.Get<IAuth>();

共享项目

 public partial class PhoneAuthPage : ContentPage
{
      IAuth auth;

        public PhoneAuthPage()
        {
            InitializeComponent();

            auth = DependencyService.Get<IAuth>();
       }
       ...
}

安卓项目

[assembly: Dependency(typeof(AuthDriod))]
namespace TestApp_Firebase.Droid.Views.PhoneViews
{
    public class AuthDriod : PhoneAuthProvider.OnVerificationStateChangedCallbacks,IAuth
    {
...
}

AppShell.xaml

<Shell ...
   xmlns:local="clr-namespace:TestApp_Firebase.Views"
   xmlns:PhoneViews="clr-namespace:TestApp_Firebase.vPhone"
   ...>

<FlyoutItem Title="Main Home Page" Icon="icon_about.png">
    <ShellContent Route="MainHomePage" ContentTemplate="{DataTemplate local:MainHomePage}" />
</FlyoutItem>
<FlyoutItem Title="Phone Auth Page" Icon="icon_about.png">
    <ShellContent Route="PhoneAuthPage" ContentTemplate="{DataTemplate PhoneViews:PhoneAuthPage}" />
</FlyoutItem>

</Shell>