Question

I’m trying to call an overriden property from a base constructor but I’m receiving a System.Reflection.TargetInvovationException(“Object reference not set to an instance of an object.”). Why is this error being thrown and can anything be done to avoid it?

I would have expected the constructor to have just called the overriden property.

Here is a stripped down example:

// Call that generates exception
var foo = new Foo();

public class Foo : Bah {

    public Foo() : base("Foo!") {}

    public override string Name {
        get { return _name + "123"; }
        set { _name = value; }
    }
}

public class Bah {

    protected string _name;

    public Bah(string name) {
        Name = name; // << -- Exception here
    }

    public virtual string Name {
        get { return _name; }
        set { _name = value; }
    }
}

Answer 1

You have some other issue going on. The code, as typed, works. Try this fully functional program to see, which prints (as expected) “Foo!123”:

using System;

namespace Test
{
    public class Program
    {
        private static void Main()
        {
            var foo = new Foo();
            Console.WriteLine(foo.Name);
            Console.ReadKey();
        }
    }

    public class Foo : Bah
    {
        public Foo() : base("Foo!") { }

        public override string Name
        {
            get { return _name + "123"; }
            set { _name = value; }
        }
    }

    public class Bah
    {
        protected string _name;

        public Bah(string name)
        {
            Name = name; // << -- No Exception here (or anywhere!)
        }

        public virtual string Name
        {
            get { return _name; }
            set { _name = value; }
        }
    }
}

That being said, calling virtual methods (including Property accessor methods) in a constructor is a very bad idea. It can lead to very odd behavior, which is likely the culprit in your real code.