What is a NullReferenceException in .NET?

Posted by John Saunders on Stack Overflow See other posts from Stack Overflow or by John Saunders
Published on 2011-01-11T16:48:29Z Indexed on 2011/01/11 19:53 UTC
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nullreferenceexception

(I'm creating this separate question and answer because every question we get on `NullReferenceException` is really the same)

I have some code and when it executes, it throws a NullReferenceException, saying, "Object reference not set to an instance of an object.".

What does this mean, and what can I do about it?

Note again, that this is a question meant to focus answers to the canonical "what is a NullReferenceException and why did I get one" question. I do know what a NullReferenceException is, as my answer below demonstrates.

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