MongoDb - Unable to determine the serialization information

Question

I want to update a property that exists on a class that inherits from the ISettingWidgets interface.

When I run the code below, I get the error: System.InvalidOperationException: Unable to determine the serialization information for o => Convert(o.Settings.get_Item(-1).Data, ISettingWidgets).Widgets.

How can I update the widgets property?

    public static async Task SaveWidgets(Guid userId, string settingName, List<IWidget> widgets)
    {
        var db = GetCollection();

        var addDef = Builders<UserInfo>.Update.Set(o => ((ISettingWidgets)o.Settings[-1].Data).Widgets, widgets);
        await coll.UpdateOneAsync(p => p.UserId == userId && p.Settings[-1].Name == settingName, addDef);
    }
    -----------------
    public class UserInfo {
          public List<Setting> Settings { get; set; }
    }

    public class Setting
    {
       public string Name { get; set; }
       public ISettingItem Data { get; set; }
    }

    public class HomePageSettings : ISettingItem, ISettingWidgets
    {
        public List<IWidget> Widgets { get; set; }

        [BsonDefaultValue(9)]
        public int ContentWidth { get; set; }
    }

    public class ProfilePageSettings : ISettingItem
    {
        [BsonDefaultValue(9)]
        public int ContentWidth { get; set; }
    }

    public interface ISettingWidgets
    {
        public List<IWidget> Widgets { get; set; }
    }

    public interface ISettingItem
    {
    }