DOCUMENT:Q158978  04-AUG-2001  [visualc]
TITLE   :FIX: SQL Debugger Stops Working
PRODUCT :Microsoft C Compiler
PROD/VER:4.2
OPER/SYS:
KEYWORDS:kberrmsg kbinterop kbDebug kbEEdition kbSQL kbVC kbSQLProg

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The information in this article applies to:

 - Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2, used with:
    - the operating system: Microsoft Windows NT 
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SYMPTOMS
========

After working for a while, the SQL Debugger starts to skip breakpoints set in
SQL code.

The Event Viewer log on the server reveals the following error message:

   CreateDispatch failed (Class not registered). Check to make sure
   Automation manager is running on debugger machine.

CAUSE
=====

There is a bug in Autprx32.dll (version 4.00.2415) that shipped with Visual C++
Enterprise Edition, version 4.2, that causes leaks of thread local storage
indices each time it completes a load and unload cycle.

There is a per process limit of 64 thread local storage indices on Windows NT.

While remote SQL debugging is in process, Autprx32.dll is loaded and unloaded on
the server. It is unloaded each time the number of remote debugging sessions
hits zero.

The debugger starts to skip breakpoints set in SQL code after approximately 25
load/unload cycles of Autprx32.dll.

RESOLUTION
==========

To resolve this problem, stop and restart the SQL Server.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug was corrected in Visual C++ version 5.0.

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

This problem only happens during remote debugging (when Visual C++ and SQL
Server reside on different computers). It doesn't happen during local debugging
(when Visual C++ and SQL Server reside on the same computer).

Additional query words: kbVC420bug kbDSupport

======================================================================
Keywords          : kberrmsg kbinterop kbDebug kbEEdition kbSQL kbVC kbSQLProg 
Technology        : kbVCsearch kbAudDeveloper kbVC32bitSearch
Version           : 4.2
Issue type        : kbbug
Solution Type     : kbfix

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