1. Object Reference Not Set To An Instance Of An Object. C#

This question already has an answer here:

• What is a NullReferenceException, and how do I fix it? 31 answers

I am receiving this error and I'm not sure what it means?

Object reference not set to an instance of an object.

John Saundersmohammad rezamohammad reza

Object obj; When we do obj = new object ; Then a new object is created on the heap and the reference to that newly created object is assigned to variable obj. If obj contains null and you try to perform any operation on object obj you will get a NUll referenceException or Object reference not set to an instance of an object. A forum user also remarks that another way to get the object reference not set to an instance of an object is if you have assigned a value to a null object. He recommends that you always check if an object that could be null is null. When I turn on my Laptop, dialogue box show 'object reference not set to an instance of an object' problem. Any suggestion,How to fix that one?

marked as duplicate by Bill the LizardDec 23 '14 at 19:41

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

8 Answers

Variables in .NET are either reference types or value types. Value types are primitives such as integers and booleans or structures (and can be identified because they inherit from System.ValueType). Boolean variables, when declared, have a default value:

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Reference types, when declared, do not have a default value:

If you try to access a member of a class instance using a null reference then you get a System.NullReferenceException. Which is the same as Object reference not set to an instance of an object.

The following code is a simple way of reproducing this:

This is a very common error and can occur because of all kinds of reasons. The root cause really depends on the specific scenario that you've encountered.

If you are using an API or invoking methods that may return null then it's important to handle this gracefully. The main method above can be modified in such a way that the NullReferenceException should never be seen by a user:

All of the above really just hints of .NET Type Fundamentals, for further information I'd recommend either picking up CLR via C# or reading this MSDN article by the same author - Jeffrey Richter. Also check out, much more complex, example of when you can encounter a NullReferenceException.

Some teams using Resharper make use of JetBrains attributes to annotate code to highlight where nulls are (not) expected.

IainIainJayJay

In a nutshell it means. You are trying to access an object without instantiating it. You might need to use the 'new' keyword to instantiate it first i.e create an instance of it.

For eg:

You will have to use:

Hope I made it clear.

Not to be blunt but it means exactly what it says. One of your object references is NULL. You'll see this when you try and access the property or method of a NULL'd object.

It means you did something like this.

And without doing

if(myObject!=null), you go ahead do myObject.Method();

Liam

Object Reference Not Set To An Instance Of An Object. C#

J.W.J.W.

Most of the time, when you try to assing value into object, and if the value is null, then this kind of exception occur.Please check this link.

for the sake of self learning, you can put some check condition. like

Syed Tayyab AliSyed Tayyab Ali

what does this error mean? Object reference not set to an instance of an object.

exactly what it says, you are trying to use a null object as if it was a properlyreferenced object.

TStamperTStamper

If I have the class:

and I then do:

The second line throws this exception becuase I'm calling a method on a reference type object that is null (I.e. has not been instantiated by calling myClass = new MyClass())

LiamLiam

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Hi Swadhin,

•When exactly do you get this error message?

•Do you have Visual Studio installed?

•Were there any changes made on the computer prior to the issue?

This error seems to be related to Visual Studio or third-party applications. Follow these steps and check:

Step 1:

Check if you face the similar issue in Safe Mode with networking, if not you can try putting your computer in a Clean Boot state in normal mode and check if it helps:

Step 2:

Clean boot helps eliminate software conflicts. Follow the Microsoft KB article to perform clean boot on the computer:

How to perform a clean boot to troubleshoot a problem in Windows 8, Windows 7, or Windows Vista

Disclaimer: After you have finished troubleshooting, follow these steps from section “How to reset the computer to start as usual after clean boot troubleshooting”to reset the computer to start as usual.

You may also refer these articles regarding 'error object reference not set to an instance of an object'

Hope this helps. If you need further assistance with Windows, let us know and will be glad to help.