Object Reference Error Before Running The Application

[Jeff]

I'm getting an Object Reference error before I even run my app, and I'm not
sure where to look to find the cause. I'd appreciate your help.

When I open my Windows Application project, the following Microsoft
Development Environment error message displays:

"Object reference not set to an instance of an object."

Then when I access the design view of one of my forms, the controls on the
form are hidden behind an error 'display' showing the text at the end of
this post. When I run the app, it seems to run OK. When I open other
projects, I don't get the error, so I'm guessing it's caused by something in
my app. But it would seem that Debug is of no help, since the error occurs
without running the app, and no error appears when I run the app.

Interesting additional observation: The problem only occurs when I open the
project to a class or module code window (since it was the active window
when I last closed the project). When I open the project to a design view
of a form, the error doesn't appear. Oh, and I've also tried
reinstalling/repairing Visual Studio, and that hasn't helped. I'm using
VB.NET.

Any suggestions???

Thanks for your help.

- Jeff


Here's the error text displayed on the form:

System.NullReferenceException: Object reference not set to an instance of an
object.
at ControlInfoView.Connect.cc1dac46909c42ab()
at ControlInfoView.Connect.dd3392f59d8e3f48(Object e0292b9ed559da7d,
EventArgs fbf34718e704c6bc)
at System.Windows.Forms.Control.OnResize(EventArgs e)
at System.Windows.Forms.Form.OnResize(EventArgs e)
at System.Windows.Forms.Control.OnSizeChanged(EventArgs e)
at System.Windows.Forms.Control.UpdateBounds(Int32 x, Int32 y, Int32 width,
Int32 height, Int32 clientWidth, Int32 clientHeight)
at System.Windows.Forms.Control.UpdateBounds()
at System.Windows.Forms.Control.WmMove(Message& m)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
at System.Windows.Forms.ContainerControl.WndProc(Message& m)
at System.Windows.Forms.Form.WndProc(Message& m)
at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Design.DesignerWindowTarget.DefWndProc(Message& m)
at System.Windows.Forms.Design.ControlDesigner.DefWndProc(Message& m)
at System.Windows.Forms.Design.ControlDesigner.WndProc(Message& m)
at System.Windows.Forms.Design.ParentControlDesigner.WndProc(Message& m)
at System.Windows.Forms.Design.ScrollableControlDesigner.WndProc(Message& m)
at System.Windows.Forms.Design.DocumentDesigner.WndProc(Message& m)
at System.Windows.Forms.Design.FormDocumentDesigner.WndProc(Message& m)
at System.Windows.Forms.Design.DesignerWindowTarget.OnMessage(Message& m)

 

[Guest]

Hi Jeff

It sounds like there is a problem creating an object (probably ControlInfoView) on the form in Design View. Remember that the Design View in VS.NET is actually going to create instances of objects and display them so exceptions can still occur and it looks like this is what is happening

If you had the design view for this form open in the project when it was last closed, VS.NET will open the form and create all of the objects on it when the project is re-loaded; thus the error will occur when VS.NET is started

Try closing the solution, deleting the .suo file and re-opening the solution file - if the error goes away then it is a problem with creating the object on the form. If that is the case then you know where to start looking.

 

[Jeff]

Well, the problem is still occurring, but I've done some additional testing.

I've distilled the problem down to the MainMenu control. It may occur with
other controls; I just haven't tested beyond this one. I've re-created the
problem by simply creating a new project and adding a MainMenu control to
Form1. Here's what I've done:

1. Start a new Windows Application: (I named mine MenuTest)
(A new project is created, and the IDE opens showing Form1)

2. Add a Main Menu to Form1 by double-clicking the MainMenu control in the
toolbox

3. Save the Project

4. Build the Solution

5. Exit VB.NET

6. Re-Launch VB.NET, open the project

7. View the Design view of Form1

8. Click the MainMenu1 control --> Error!

Microsoft Development Environment
Object reference not set to an instance of an object.

I then added a menu item, saved/built, closed/opened the IDE. Clicking the
MainMenu1 control did NOT raise the error. But if I then viewed the code
window for Form1 and then closed/opened the IDE (so the code window was
displayed as the most recent document), the error was displayed.

If I follow PocketNerd's suggestion by deleting the suo file and re-opening
the project, the problem doesn't occur -- until I next open the project
again, when the problem recurs.

I still don't know how to solve the problem! Does anyone have any
suggestions?

- Jeff

Hi Jeff,

It sounds like there is a problem creating an object (probably

ControlInfoView) on the form in Design View. Remember that the Design View
in VS.NET is actually going to create instances of objects and display them
so exceptions can still occur and it looks like this is what is happening.

If you had the design view for this form open in the project when it was

last closed, VS.NET will open the form and create all of the objects on it
when the project is re-loaded; thus the error will occur when VS.NET is
started.

Try closing the solution, deleting the .suo file and re-opening the

solution file - if the error goes away then it is a problem with creating
the object on the form. If that is the case then you know where to start
looking.