Can't Run My App on Android 5.1 (API 22)

Installed from signed APK

Target Framework: Android 8.1
Target Android Version: Android 8.1
Minimum Android Version: Android 4.4

This is the error i get from device log tool:

System.NullReferenceException: Object reference not set to an instance of an object
  at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.InternalSetPage (Xamarin.Forms.Page page) [0x0006f] in <99988d4ab8d144898ef5bc7586876d75>:0 
  at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.SetMainPage () [0x0000c] in <99988d4ab8d144898ef5bc7586876d75>:0 
  at Xamarin.Forms.Platform.Android.FormsAppCompatActivity.LoadApplication (Xamarin.Forms.Application application) [0x0026f] in <99988d4ab8d144898ef5bc7586876d75>:0 
  at SampleApp.Droid.MainActivity.OnCreate (Android.OS.Bundle bundle) [0x00028] in <eaa39f9ef27d400ebfed424165f990c2>:0 
  at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_ (System.IntPtr jnienv, System.IntPtr native__this, System.IntPtr native_savedInstanceState) [0x0000f] in <818821ea7e204c78a45bc29cdc69e744>:0 
  at (wrapper dynamic-method) System.Object.fe8f1617-954f-4716-901a-433b7f8b44bf(intptr,intptr,intptr)