FIX: Access Violation Running Visual FoxPro on Windows NT 4.0 (168277)

SYMPTOMS

Running an application created with Visual FoxPro for Windows may cause the an error similar to the following under Windows NT version 4.0:

An application error has occurred and an application error log is being generated.

<vfp.exe or name of runtime .exe file> Exception: access violation (0xc0000005), Address: 0x100a4669"

This most commonly occurs when running a form that repeatedly runs a second form containing a grid, but may also occur in circumstances where multiple forms or grids are not involved.

The error address varies based on the version of Visual FoxPro, and whether the forms are running under the development environment (DE) or the runtime environment (executable).

    Platform                  Dev. Env. Address    Runtime Address
   ----------               -------------------  -----------------
   VFP 5.0 (Build 344)           0x00401a37         0x100a4669
   VFP 5.0a (Build 402)          0x0040118d         0x100017bf

The build number can be found by using the VERSION() function. Visual FoxPro 5.0 build 344 returns the following version information:

   Visual FoxPro 05.00.00.0344 for Windows

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

MORE INFORMATION

The conditions under which this occurs are as follows:

A value to search for is entered in form 1.
A second form is displayed containing a grid, which displays records that match the value from step 1.
A record is selected in the grid and the second form is closed.
Steps 1 through 3 are repeated.

This happens only in rare instances and is more likely to occur in complex applications. It does not occur under Windows 95, nor does it occur in Visual FoxPro 3.0b. If one of the exact addresses listed above does not appear, the issue is distinct from the one described in this article.