What does the error "object reference not set to an instance of an object" mean?

General Discussions
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1

What does the error “object reference not set to an instance of an object” mean?

I am encountering this error and I’m unsure about its cause. What does “object reference not set to an instance of an object” indicate, and how can I resolve it?

2

I’ve seen this error too many times in my career, and it usually boils down to one thing—dereferencing a null object.

The “object reference not set to an instance of an object” error happens when you try to access a property or method of an object that hasn’t been initialized. The simplest fix? Always check for null before using an object:

if (myObject != null)
{
    Console.WriteLine(myObject.Property);
}
else
{
    Console.WriteLine("Object is null");
}

A quick null check can save you from unexpected crashes.

3

Building on what @mark-mazay said, checking for null is great, but why not prevent it in the first place?"

Another reason you might see the “object reference not set to an instance of an object” error is that the object was never initialized. The best practice is to ensure objects are instantiated before use:

MyClass myObject = new MyClass(); // Now it's a valid instance
myObject.Property = "Some Value";

This way, your variables always hold valid references, eliminating the risk of null reference errors.

4

Great points, both of you guys! But sometimes, you can’t always guarantee initialization—so let’s make our code safer."

Instead of manually checking for null every time, use the null-coalescing (??) or null-conditional (?.) operators:

string value = myObject?.Property ?? "Default Value";
Console.WriteLine(value);

Now, if myObject is null, you won’t get the “object reference not set to an instance of an object” error—your program will gracefully fall back to a default value.