DOCUMENT:Q190487  17-JUL-2001  [visualc]
TITLE   :PRB: MFC Debug DLLs Are Not Compatible Between Versions
PRODUCT :Microsoft C Compiler
PROD/VER:winnt:4.2,5.0,6.0
OPER/SYS:
KEYWORDS:kbDebug kbDLL kbMFC kbVC420 kbVC500 kbVC600 kbGrpDSMFCATL

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The information in this article applies to:

 - The Microsoft Foundation Classes (MFC), used with:
    - Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2 
    - Microsoft Visual C++, 32-bit Professional Edition, version 4.2 
    - Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0 
    - Microsoft Visual C++, 32-bit Professional Edition, version 5.0 
    - Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
    - Microsoft Visual C++, 32-bit Professional Edition, version 6.0 
    - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SYMPTOMS
========

Various errors or asserts can occur when you attempt to run a debug version of
an MFC application with the MFC debug DLLs of another version. Possible errors
include:

    - Ordinal could not be found.

    - Access violation.

This occurs if you attempt to debug an MFC application built with Visual C++ 5.0
in Visual C++ 6.0 and vice versa. This can also occur if you run your MFC debug
application on a machine that does not have the corresponding debug DLLs
installed.

CAUSE
=====

Debug versions of MFC are not binary compatible with previous versions. However,
this problem does not occur with release builds because they are binary
compatible between versions.

RESOLUTION
==========

To debug an MFC project built with Visual C++ 5.0 in Visual C++ 6.0, you must
rebuild the project. To run a debug version of an MFC project on a machine that
does not have Visual C++ installed, make sure the proper version of the MFC
debug DLLs are installed. Note that redistribution of MFC debug DLLs is a
violation of the Visual C++ license agreement.

STATUS
======

This behavior is by design.

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

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

1. Build a DEBUG Build MFC application with Visual C++ 5.0.

2. Copy the .exe file to a machine with Visual C++ 6.0 installed.

3. Run the .exe file.

   RESULT: Runtime errors such as:

   The ordinal 3255 could not be located in the dynamic link library
   MFCO42D.DLL

   -or-

   Unhandled exception in thisisatest.exe: 0xC0000005: Access Violation.

(c) Microsoft Corporation 1998, All Rights Reserved. Contributions by Mike
Francis, Microsoft Corporation.


Additional query words: 0xC0000005

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Keywords          : kbDebug kbDLL kbMFC kbVC420 kbVC500 kbVC600 kbGrpDSMFCATL 
Technology        : kbAudDeveloper kbMFC
Version           : winnt:4.2,5.0,6.0
Issue type        : kbprb

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

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