FIX: NVL() Releases Object Ref and Causes Fatal Error C0000005 (221743)


The information in this article applies to:

  • Microsoft Visual FoxPro for Windows 5.0
  • Microsoft Visual FoxPro for Windows 5.0a
  • Microsoft Visual FoxPro for Windows 6.0
This article was previously published under Q221743

SYMPTOMS

Calling the NVL() function multiple times in Visual FoxPro 5.0 causes the following error message:
Property <property name> is not method or event.
If you click the Ignore button in the error dialog box and run the program again, you normally see the following error:
An application error has occurred and an application log is being generated.
VFP.exe
Exception: access violation (0x0000005), Address: <memory address>
In some instances, the first error message is skipped and the second error is displayed.

The following error can also occur:
The instruction at "0x00401e44" referenced memory at "0x010bb018". The memory could not be "read".
In Visual FoxPro 6.0, the following error often appears after calling the NVAL() function the third time:
Fatal error: Exception code: C0000005

CAUSE

The NVL() function saved the handle, but it released the object reference.

STATUS

Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

This bug was corrected in Visual Studio 6.0 Service Pack 3.

For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base:

194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed

MORE INFORMATION

Steps to Reproduce Behavior

  1. Create a program that contains the following code:
    ox = CreateObject("Lbltest")
ox.Test()
ox.Test()
ox.Test()

Define Class Lbltest as Label
 Procedure Test
 oObj = NVL(.NULL.,This)
 ?oObj.name
 EndProc
 
Enddefine
  2. Run the program. After accessing the Test procedure the third time, one of the errors listed in the SYMPTOMS section above appears.
Modification Type:MajorLast Reviewed:10/16/2002
Keywords:kbBug kberrmsg kbOOP kbVS600sp3fix KB221743
©2002 Microsoft Corporation. All rights reserved.