ListViewAdapter.IsEnabled android.runtime.JavaProxyThrowable: System.NullReferenceException: Object

Hello, I have this Crash:

Xamarin caused by: android.runtime.JavaProxyThrowable: System.NullReferenceException: Object reference not set to an instance of an object
Xamarin.Forms.Platform.Android.ListViewAdapter.IsEnabled(int position)<173f39d71f0d4d928f5bbea42e96ffa8>:0
Android.Widget.BaseAdapter.n_IsEnabled_I(IntPtr jnienv, IntPtr native__this, int position):0
at (wrapper dynamic-method) System.Object:559d609d-c704-4246-85cd-c185afe055df (intptr,intptr,int)
md5b60ffeb829f638581ab2bb9b1a7f4f3f.ListViewAdapter.n_isEnabled(Native Method)
md5b60ffeb829f638581ab2bb9b1a7f4f3f.ListViewAdapter.isEnabled()ListViewAdapter.java:108
android.widget.HeaderViewListAdapter.isEnabled()HeaderViewListAdapter.java:159
android.widget.ListView.setupChild()ListView.java:1988
android.widget.ListView.makeAndAddView()ListView.java:1938
android.widget.ListView.fillDown()ListView.java:719
android.widget.ListView.fillSpecific()ListView.java:1391
android.widget.ListView.layoutChildren()ListView.java:1746
android.widget.AbsListView.onLayout()AbsListView.java:2860
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
android.support.v4.widget.SwipeRefreshLayout.onLayout()SwipeRefreshLayout.java:636
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
md5b60ffeb829f638581ab2bb9b1a7f4f3f.ListViewRenderer.n_onLayout(Native Method)
md5b60ffeb829f638581ab2bb9b1a7f4f3f.ListViewRenderer.onLayout()ListViewRenderer.java:65
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
com.xamarin.forms.platform.android.FormsViewGroup.measureAndLayout()FormsViewGroup.java:28
md5b60ffeb829f638581ab2bb9b1a7f4f3f.VisualElementRenderer_1.n_onLayout(Native Method)
md5b60ffeb829f638581ab2bb9b1a7f4f3f.VisualElementRenderer_1.onLayout()VisualElementRenderer_1.java:72
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
com.xamarin.forms.platform.android.FormsViewGroup.measureAndLayout()FormsViewGroup.java:28
md5b60ffeb829f638581ab2bb9b1a7f4f3f.ScrollViewContainer.n_onLayout(Native Method)
md5b60ffeb829f638581ab2bb9b1a7f4f3f.ScrollViewContainer.onLayout()ScrollViewContainer.java:46
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
android.widget.FrameLayout.layoutChildren()FrameLayout.java:344
android.widget.FrameLayout.onLayout()FrameLayout.java:281
android.widget.ScrollView.onLayout()ScrollView.java:2562
md5b60ffeb829f638581ab2bb9b1a7f4f3f.ScrollViewRenderer.n_onLayout(Native Method)
md5b60ffeb829f638581ab2bb9b1a7f4f3f.ScrollViewRenderer.onLayout()ScrollViewRenderer.java:91
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
md5b60ffeb829f638581ab2bb9b1a7f4f3f.VisualElementRenderer_1.n_onLayout(Native Method)
md5b60ffeb829f638581ab2bb9b1a7f4f3f.VisualElementRenderer_1.onLayout()VisualElementRenderer_1.java:72
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
com.xamarin.forms.platform.android.FormsViewGroup.measureAndLayout()FormsViewGroup.java:28
md5270abb39e60627f0f200893b490a1ade.NavigationPageRenderer.n_onLayout(Native Method)
md5270abb39e60627f0f200893b490a1ade.NavigationPageRenderer.onLayout()NavigationPageRenderer.java:65
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
com.xamarin.forms.platform.android.FormsViewGroup.measureAndLayout()FormsViewGroup.java:28
md5270abb39e60627f0f200893b490a1ade.MasterDetailContainer.n_onLayout(Native Method)
md5270abb39e60627f0f200893b490a1ade.MasterDetailContainer.onLayout()MasterDetailContainer.java:45
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
android.support.v4.widget.DrawerLayout.onLayout()DrawerLayout.java:1193
md5270abb39e60627f0f200893b490a1ade.MasterDetailPageRenderer.n_onLayout(Native Method)
md5270abb39e60627f0f200893b490a1ade.MasterDetailPageRenderer.onLayout()MasterDetailPageRenderer.java:68
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
md5b60ffeb829f638581ab2bb9b1a7f4f3f.PlatformRenderer.n_onLayout(Native Method)
md5b60ffeb829f638581ab2bb9b1a7f4f3f.PlatformRenderer.onLayout()PlatformRenderer.java:55
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
android.widget.RelativeLayout.onLayout()RelativeLayout.java:1080
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
android.widget.FrameLayout.layoutChildren()FrameLayout.java:344
android.widget.FrameLayout.onLayout()FrameLayout.java:281
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
android.widget.LinearLayout.setChildFrame()LinearLayout.java:1742
android.widget.LinearLayout.layoutVertical()LinearLayout.java:1585
android.widget.LinearLayout.onLayout()LinearLayout.java:1494
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
android.widget.FrameLayout.layoutChildren()FrameLayout.java:344
android.widget.FrameLayout.onLayout()FrameLayout.java:281
com.android.internal.policy.PhoneWindow$DecorView.onLayout()PhoneWindow.java:3175
android.view.View.layout()View.java:18010
android.view.ViewGroup.layout()ViewGroup.java:5911
android.view.ViewRootImpl.performLayout()ViewRootImpl.java:2784
android.view.ViewRootImpl.performTraversals()ViewRootImpl.java:2477
android.view.ViewRootImpl.doTraversal()ViewRootImpl.java:1544
android.view.ViewRootImpl$TraversalRunnable.run()ViewRootImpl.java:7616
android.view.Choreographer$CallbackRecord.run()Choreographer.java:911
android.view.Choreographer.doCallbacks()Choreographer.java:686
android.view.Choreographer.doFrame()Choreographer.java:622
android.view.Choreographer$FrameDisplayEventReceiver.run()Choreographer.java:897
android.os.Handler.handleCallback()Handler.java:739
android.os.Handler.dispatchMessage()Handler.java:95
android.os.Looper.loop()Looper.java:148
android.app.ActivityThread.main()ActivityThread.java:7406
java.lang.reflect.Method.invoke(Native Method)
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run()ZygoteInit.java:1230
com.android.internal.os.ZygoteInit.main()ZygoteInit.java:1120

Any ideas?

Thanks