Knowledge Base

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

Article ID: 182138

Article Last Modified on 12/8/2000

Microsoft Visual FoxPro 5.0 Standard Edition, when used with:
- Microsoft Windows 95
Microsoft Visual FoxPro 5.0a, when used with:
- Microsoft Windows 95

This article was previously published under Q182138

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

Install Visual FoxPro (VFP) 5.0x on a Windows 95 computer.
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.
From the Tools menu, click Class Browser.
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: kbprb kbpending KB182138