Microsoft KB Archive/171487

= FIX: Crash When Assigning Uninitialized Object to Tag =

Article ID: 171487

Article Last Modified on 11/18/2003

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APPLIES TO


 * Microsoft Visual Basic 5.0 Learning Edition
 * Microsoft Visual Basic 5.0 Professional Edition
 * Microsoft Visual Basic 5.0 Enterprise Edition

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This article was previously published under Q171487



SYMPTOMS
Attempting to set the Tag property of one of the Windows Common Controls (COMCTL32.OCX) at run-time may result in the following error and cause the application to terminate:

"VB5 caused an invalid page fault in module COMCTL32.OCX at 0137:202cb2a8."



CAUSE
This problem occurs when the object variable that you are trying to assign to the Tag property is uninitialized or is null.



RESOLUTION
In Visual Basic 5.0, you can work around the problem by checking the value of the variable before assigning it to the Tag property: Dim x As Object '...  If x Is Nothing Then '  Else StatusBar1.Panels(1).Tag = x  End If



STATUS
Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been fixed in Visual Studio 97 Service Pack 2.

For more information on the Visual Studio 97 Service Pack 2, please see the following article in the Microsoft Knowledge Base:

170365 INFO: Visual Studio 97 Service Packs - What, Where, and Why

For a list of the Visual Basic 5.0 bugs that were fixed in the Visual Studio 97 Service Pack 2, please see the following article in the Microsoft Knowledge Base:

171554 INFO: Visual Basic 5.0 Fixes in Visual Studio 97 Service Pack 2



MORE INFORMATION
With Visual Studio 97 Service Pack 2 installed, the above scenario correctly yields with the following trappable run-time error.

Run-time error '91':

Object variable or With block not set.

Additional query words: listview toolbar treeview

Keywords: kberrmsg kbbug kbfix kbvbp500sp2fix kbvs97sp2fix KB171487

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