2

I got the error having the stack trace...

System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'Button'.
at System.Windows.Forms.Control.CreateHandle()
at System.Windows.Forms.Control.get_Handle()
at System.Windows.Forms.Control.PointToScreen(Point p)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ButtonBase.WndProc(Message& m)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

The code producing this error is....

Friend Sub GoHome(ByVal sender As Form)
  InTransit = True
  sender.Close()
  fMain.Show()
End Sub

It doesn't give error when I just switch the order of the .show and .close method

Friend Sub GoHome(ByVal sender As Form)
  InTransit = True
  fMain.Show()
  sender.Close()
End Sub

Can you please tell me why for the first case it gives error and why in second case it doesn't??

svick
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rai
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  • More interesting information…. 1 I happens only when the application is virtualized (by Citrix) It never happen if it run in the same computer. 2 when the code include a message box it doesn’t give the error. This code works fine without any error… Friend Sub GoHome(ByVal sender As Form) InTransit = True MsgBox(“Any message”) sender.Close() fMain.Show() End Sub – rai Feb 16 '12 at 15:40

1 Answers1

0

Are sender and fMain the same object in this case?

If so... when you call sender.Close you're effectively calling fMain.Close, and the Close method will be disposing that object behind-the-scenes. If you subsequently call fMain.Show then you're calling it on an object that you just disposed, hence the error.

Or, alternatively...

Maybe sender is one of the child controls on fMain?

You call sender.Close, disposing the child control. You then call fMain.Show which attempts to do something with the child controls belonging to fMain. The error occurs when it tries to do that particular something with the child control that you just disposed.

LukeH
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