"Object reference not set to an instance of an object" when it shouldn't be

Question

I use this code:

NewDesign.CardImage.Image.Save(System.IO.Path.GetDirectoryName(NewDesign.SaveFileDialog1.FileName) + "\" + My.Settings.SaveLoc + "_cardimage" + ".png")

My.settings.SaveLoc is literally just a string which contains a filename, for example: test.

It's value is set using:

My.Settings.SaveLoc = System.IO.Path.GetFileName(SaveFileDialog1.FileName)

It worked in the past but suddenly out of nowhere it stopped working.

I used the breakpoints and SaveFileDialog1.FileName is exactly where expected, in this case "R:\My Pictures\Test Folder", also SaveLoc contains the value I expect it to.

But when it's attempting to save the image, it gives me the error of "Object reference not set to an instance of an object" and I honestly don't know what I could've possibly done wrong.

@SLaks it's now not showing any errors at all and skipping that line of code — Dominik H, Jan 03 '16 at 02:22
There is not nearly enough content or context to be much help. What is `NewDesign` for instance? It sort of looks like a default form reference. — Ňɏssa Pøngjǣrdenlarp, Jan 03 '16 at 13:45
I'm sorry but how is it a duplicate? If anything, it's similar I know what the problem means, I just didn't know why I got the problem — Dominik H, Jan 03 '16 at 13:58
Its a dupe because the other goes into great detail on how to find and fix NREs and the core problem for almost all NREs is the same thing. In that little snippet, there are 3 candidates which could be null — Ňɏssa Pøngjǣrdenlarp, Jan 03 '16 at 14:13
I suppose but the type of question is NOT a duplicate, this person is asking for what the problem is and how to fix it whereas I'm asking why it's happening in my case, either way; I fixed the issue — Dominik H, Jan 03 '16 at 14:23
*why* is relevant; how to find it and fix it is not. Since the answer would just be a repeat of what is there, it is a dupe. There is no shame in that. — Ňɏssa Pøngjǣrdenlarp, Jan 04 '16 at 01:05
@Plutonix exactly, I'm asking why, not how. So the answer would've been different. — Dominik H, Jan 05 '16 at 02:16

score 1 · Answer 1 · answered Jan 03 '16 at 02:07

1

NewDesign.CardImage.Image is almost certainly not initialized. Perhaps this control can't be accessed that way until the handle is created. Some of the image containers have bad behavior like that.

Incidentally,

NewDesign is probably a form in which you dropped a SaveFileDialog on. The ability to access non-static member by form name is VB6 compatibility function that's best NOT used.

answered Jan 03 '16 at 02:07

Joshua

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What can I do instead? If I use a DIm or ReadOnly variable to reference the NewDesign form I'm only getting errors about stackOverFlowExceptions and what not. – Dominik H Jan 03 '16 at 02:17
Update: I created a reference to the form, ran the program, it showed errors, deleted the reference, and it works again. What on earth is going on? Edit: that was a lie, it works in a way that it shows absolutely no errors and just skips the saving image part – Dominik H Jan 03 '16 at 02:19
Sounds like a very serious code structure problem. – Joshua Jan 03 '16 at 03:14
Oh no, is that the only issue it could be? – Dominik H Jan 03 '16 at 03:18
StackoverflowException at New Something is usually really bad. – Joshua Jan 03 '16 at 03:21
Hmm I just discovered that they are basically referring to each other, the save image class is referring to NewDesign and the NewDesign class is referring to the save image class simultaneously, that appears to be causing this error. But how would I reference both without this error being caused? – Dominik H Jan 03 '16 at 03:33
edit in a lot more so we can see it. – Joshua Jan 03 '16 at 03:36

"Object reference not set to an instance of an object" when it shouldn't be

1 Answers1