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Q230204: SNA Server Fails Due to Access Violation in SNADMOD!RpcRouteProc

Article: Q230204
Product(s): Microsoft SNA Server
Version(s): WINDOWS:3.0,3.0SP1,3.0SP2,3.0SP3,4.0,4.0SP1,4.0SP2
Operating System(s): 
Keyword(s): kbsna400sp3fix
Last Modified: 08-MAY-2002

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The information in this article applies to:

- Microsoft SNA Server, versions 3.0, 3.0SP1, 3.0SP2, 3.0SP3, 4.0, 4.0SP1, 4.0SP2 
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SYMPTOMS
========

The SNA Server service (Snaservr.exe) may fail unexpectedly or may stop
accepting new client connections when the access violation in
SNADMOD!RpcRoutProc occurs. This results in one or both of the following:

- Previously-connected users lose their host (mainframe or AS/400) sessions.
- New users are unable to obtain a new host session.

If the Windows NT Server where SNA Server is running is configured with
Drwtsn32.exe as the default debugger, a Drwtsn32.log entry may be generated when
this failure occurs, indicating a FAULT in the top-level routine along with the
following stack-back trace (which may vary):

      snadmod!RpcRouteProc+0x400
      snadmod!sepdq2_int+0x122
      ntdll!RtlLeaveCriticalSection+0x1d
      snadmod!sbpdin_int+0x23d
      snadmod!sbpdin+0x25
      snaservr!sbpcdin+0x50
      snaservr!sbpsched+0x2ac
      snaservr!sbpgmain+0x25
      snasvc!ServiceMainFunction+0x140
      advapi32!ScSvcctrlThreadA+0xe
      kernel32!BaseThreadStart+0x51

In the reported instances of this problem, the SNA Server systems had to be
rebooted to recover.

CAUSE
=====

The access violation occurs when an SNA Server RPC Response message is
inadvertently routed to the SNA Server service. The SNA Server service is unable
to interpret this message, which causes the access violation to occur.

RESOLUTION
==========

SNA Server 4.0
--------------

To resolve this problem, obtain the latest service pack for SNA Server version
4.0. For additional information, please see the following article in the
Microsoft Knowledge Base:

  Q215838 How to Obtain the Latest SNA Server Version 4.0 Service Pack


SNA Server 3.0
--------------

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   | 
+---------------------------------+
| Snadmod.dll  | 3/11/99 | 7:45PM | 
+---------------------------------+
| snaevent.dll | 3/11/99 | 7:46PM | 
+---------------------------------+

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



STATUS
======

Microsoft has confirmed this to be a problem in Microsoft SNA Server versions
3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 4.0, 4.0 SP1, and 4.0 SP2. This problem was
first corrected in SNA Server version 4.0 Service Pack 3.

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

An exception handler was added to handle this exception whenever it may occur.
The SNA Server service will no longer fail unexpectedly or stop accepting client
connections when this occurs after the update is applied. In addition, the
following event will be logged in the Windows NT application event log if this
problem occurs after the update is applied.

  Event ID: 731
  Description: Invalid RPC Response message
  RPC Code: <value>
  Source: <value>
  Destination: <value>

Additional query words:

======================================================================
Keywords          : kbsna400sp3fix 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ400
Version           : WINDOWS:3.0,3.0SP1,3.0SP2,3.0SP3,4.0,4.0SP1,4.0SP2
Issue type        : kbbug
Solution Type     : kbfix

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