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Q171555: FIX: More Than One Sub Main May Cause EXE to Crash

Article: Q171555
Product(s): Microsoft Visual Basic for Windows
Version(s): 5.0
Operating System(s): 
Keyword(s): kbVBp500 kbVS97sp2fix kbGrpDSVB kbvbp500sp2fix
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Control Creation Edition for Windows, version 5.0 
- Microsoft Visual Basic Learning Edition for Windows, version 5.0 
- Microsoft Visual Basic Professional Edition for Windows, version 5.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 
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SYMPTOMS
========

If a project contains more than one Sub Main in different modules, it may run as
expected in the IDE and compile without errors in either native or p- code, but
will crash when run as an EXE. Visual Basic 5.0 will generate an application
error, such as:

  "The instruction at <address> referenced memory at <address>. The
  memory could not be "written"."

CAUSE
=====

To avoid this problem, either include only one parameter-less Sub Main in the
project, or install Visual Studio 97 Service Pack 2 (SP2).

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:

  Q170365 INFO: Visual Studio 97 Service Packs - What, Where, and Why

For a list of the Visual Basic 5.0 bugs that were fixed in the Visual Studio 97
Service Pack 2, please see the following article in the Microsoft Knowledge
Base:

  Q171554 INFO: Visual Basic 5.0 Fixes in Visual Studio 97 Service Pack 2

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

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

1. Start a new Standard EXE project(Project1) in Visual Basic 5.0.

2. Go to Project | Add Module, and add a .bas module(Module1) to Project1.

3. Add the following code to Module1:

        Sub Main ()
        End

4. Click on menu Project | Project1 Properties, select the General tab, and set
  the Startup object as Sub Main.

5. Click on Project | Add Class Module, and add a class module (Class1) to
  Project1.

6. Add the following code to Class1:

        Sub Main ()
        End

7. Make Project1.EXE, using either p-code or native code.

8. Run Project1.EXE. Note that Project1.EXE should crash with an Application
  Error.

Additional query words:

======================================================================
Keywords          : kbVBp500 kbVS97sp2fix kbGrpDSVB kbvbp500sp2fix 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVBA500Search kbVBA500 kbVB500 kbZNotKeyword3
Version           : 5.0
Issue type        : kbbug
Solution Type     : kbfix

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

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