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Q235723: SNA Windows 3.x Client Displays Warning 956, Won’t Unload

Article: Q235723
Product(s): Microsoft SNA Server
Version(s): WINDOWS:4.0,4.0SP1,4.0SP2,4.0SP3
Operating System(s): 
Keyword(s): sna4 kbsna400sp1 kbsna400sp2 kbsna400sp3
Last Modified: 08-MAY-2002

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The information in this article applies to:

- Microsoft SNA Server, versions 4.0, 4.0SP1, 4.0SP2, 4.0SP3 
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SYMPTOMS
========

After running one or more 16-bit Windows APPC applications on top of the SNA
Windows 3.x client (on a Windows 95 workstation), the Wnap.exe process may
display the following error message even though all SNA client applications have
ended:

  SNA Server Messager

  SNA Server Warning 956
  SNA Base cannot be terminated while its services are being used.

This problem couldn't be reproduced when running the SNA Windows 3.x client on
Windows NT. Traces reveal that the APPC applications are not calling
WinAPPCCleanup prior to termination, contributing to the problem.

CAUSE
=====

If an APPC application fails to call WinAPPCCleanup before the process
terminates, the SNA Windows 3.x client software relies on the operating system
to notify Wnap.exe that the Win16 process has ended. However, when running on
Windows 95, this was not occurring properly.

RESOLUTION
==========

A supported fix is now available from Microsoft, but it is only intended to
correct the problem described in this article and should be applied only to
systems experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the
fix. For a complete list of Microsoft Product Support Services phone numbers and
information on support costs, please go to the following address on the World
Wide Web:

  http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are normally incurred for support calls may
be canceled, if a Microsoft Support Professional determines that a specific
update will resolve your problem. Normal support costs will apply to additional
support questions and issues that do not qualify for the specific update in
question.

The English version of this fix should have the following file attributes or
later:

+-------------------------------+
| File name | Date     | Time   | 
+-------------------------------+
| Wnap.exe  | 05/20/99 | 12:06p | 
+-------------------------------+

NOTE: Because of file dependencies, the most recent fix that contains the above
files may also contain additional files.



WORKAROUND
==========

For all APPC applications, ensure that they properly call WinAPPCStartup when
the APPC process first starts, and WinAPPCCleanup before the process ends.

STATUS
======

Microsoft has confirmed this to be a problem in Microsoft SNA Server version
4.0.

Additional query words:

======================================================================
Keywords          : sna4 kbsna400sp1 kbsna400sp2 kbsna400sp3 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ400
Version           : WINDOWS:4.0,4.0SP1,4.0SP2,4.0SP3
Issue type        : kbbug
Solution Type     : kbfix

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