FIX: Crash When Assigning Uninitialized Object to Tag (171487)

The information in this article applies to:

Microsoft Visual Basic Learning Edition for Windows 5.0
Microsoft Visual Basic Professional Edition for Windows 5.0
Microsoft Visual Basic Enterprise Edition for Windows 5.0

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.

Modification Type:	Major	Last Reviewed:	11/18/2003
Keywords:	kbbug kberrmsg kbfix kbvbp500sp2fix kbVS97sp2fix KB171487