Xamarin Android App works fine on Oreo and above versions of android, but crashes otherwise

Question

I'm calling the following activity from a fragment (using Android.Support.V4.App) to upload a file from device

    var intent = new Intent();
    intent.SetType("*/*");
    intent.SetAction(Intent.ActionGetContent);
    Activity.StartActivityForResult(Intent.CreateChooser(intent, "Select Files"), 0);

When I select a file, the code successfully returns to

    protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
    {
       base.OnActivityResult(requestCode, resultCode, data);

       if (resultCode == Result.Ok) // File Attachment
       {
          ICursor returnCursor = ContentResolver.Query(uri, null, null, null, null);
          int nameIndex = returnCursor.GetColumnIndex(OpenableColumns.DisplayName);

          returnCursor.MoveToFirst();

          var fileName = returnCursor.GetString(nameIndex);

          ViewModel.Files.Add(new FileModel()
          {
             FileName = fileName,
             FileBytes = HelperClasses.FileStreamHelper.ReadFully(stream)
          });
       }    
    }

The code successfully completes the OnActivityResult method but immediately after that the app crashes with the following error

--- End of managed Java.Lang.ArrayIndexOutOfBoundsException stack trace ---
java.lang.ArrayIndexOutOfBoundsException: length=8; index=-1
    at java.util.Arrays$ArrayList.get(Arrays.java:3854)
    at android.widget.ArrayAdapter.getItem(ArrayAdapter.java:349)
    at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:405)
    at android.widget.ArrayAdapter.getView(ArrayAdapter.java:371)
    at android.widget.Spinner.makeView(Spinner.java:702)
    at android.widget.Spinner.layout(Spinner.java:650)
    at android.widget.Spinner.onLayout(Spinner.java:612)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.widget.ScrollView.onLayout(ScrollView.java:1535)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1079)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1795)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1079)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1079)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.support.design.widget.CoordinatorLayout.layoutChild(CoordinatorLayout.java:1167)
    at android.support.design.widget.CoordinatorLayout.onLayoutChild(CoordinatorLayout.java:852)
    at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:871)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at com.android.internal.policy.DecorView.onLayout(DecorView.java:724)
    at android.view.View.layout(View.java:17523)
    at android.view.ViewGroup.layout(ViewGroup.java:5612)
    at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2342)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2069)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1246)
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6301)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:871)
    at android.view.Choreographer.doCallbacks(Choreographer.java:683)
    at android.view.Choreographer.doFrame(Choreographer.java:619)
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:857)
    at android.os.Handler.handleCallback(Handler.java:751)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6077)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)

Note that the code works on Android Oreo and above version, but fails on a Nougat device.

Answer 1

I am assuming you are using the incorrect uri as it is provided via returned Intent.

Note: You need to close and dispose of your ICursor, otherwise you will leak.

Example (API 23 through 28):

protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
{
    if (resultCode == Result.Ok && requestCode == 0)
    {
        using (ICursor returnCursor = ContentResolver.Query(data.Data, null, null, null, null))
        {
            switch (returnCursor.Count)
            {
                case 0:
                    Log.Debug("SO", "File not found in media store, media store corruption possible");
                    break;
                case 1:
                    int nameIndex = returnCursor.GetColumnIndex(OpenableColumns.DisplayName);
                    returnCursor.MoveToFirst();
                    var fileName = returnCursor.GetString(nameIndex) ?? "* Name not available *";

                    // Do something with display name
                    Log.Debug("SO", fileName);

                    break;
                default:
                    Log.Debug("SO", "Multiple Files returned, OEM's Intent.CreateChoose allowed mutiple files");
                    break;
            }
            returnCursor.Close();
        }
    }
}