KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q182138: PRB: MVCOUNT May Cause Illegal Operation Error in VFP 5.0x

Article: Q182138
Product(s): Microsoft FoxPro
Version(s): WINDOWS:5.0,5.0a
Operating System(s): 
Keyword(s): kbvfp
Last Modified: 08-DEC-2000

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a, on platform(s):
   - the operating system: Microsoft Windows 95 
-------------------------------------------------------------------------------

SYMPTOMS
========

When you attempt to open a visual class library (.vcx) file in the Class
Browser, the following error may appear:

  This program performed an illegal operation and will be shutdown.

When you press the Details button, the following message appears:

  VFP caused an invalid page fault in module VFP.EXE at <memory address>.

This problem does not occur in Visual FoxPro 3.0b or when running Visual FoxPro
5.0x on a Windows NT 4.0 computer.

CAUSE
=====

The value of MVCOUNT in the Config.fpw file is greater than 34000.

RESOLUTION
==========

Set MVCOUNT to a number less than 34000.

STATUS
======

Microsoft is researching this problem and will post new information here in the
Microsoft Knowledge Base as it becomes available.

MORE INFORMATION
================

The MVCOUNT keyword allows you to control the number of variables that Visual
FoxPro can use.

Steps to Reproduce Behavior
---------------------------

1. Install Visual FoxPro (VFP) 5.0x on a Windows 95 computer.

2. Add the following to the Config.fpw file:

        MVCOUNT=65000

  Save the file and restart Visual FoxPro so it can read the new Config.fpw
  file.

  You can use any number greater than 34000.

3. From the Tools menu, click Class Browser.

4. After the Class Browser opens, attempt to open a .vcx file.

REFERENCES
==========

Visual FoxPro Help; search on: "MVCOUNT"

Additional query words: crash hang GPF fault

======================================================================
Keywords          : kbvfp 
Technology        : kbVFPsearch kbAudDeveloper
Version           : WINDOWS:5.0,5.0a
Issue type        : kbprb
Solution Type     : kbpending

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.