SNA Server Fails Due to Access Violation in SNADMOD!RpcRouteProc (230204)


The information in this article applies to:

  • Microsoft SNA Server 3.0
  • Microsoft SNA Server 4.0
This article was previously published under Q230204

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, click the following article number to view the article in the Microsoft Knowledge Base:

215838 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 that is described in this article. Apply it only to computers that are 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 about support costs, visit the following Microsoft Web site:

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

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual 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 nameDateTime
Snadmod.dll3/11/997:45PM
snaevent.dll3/11/997:46PM

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

STATUS

Microsoft has confirmed that this is 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>
Modification Type:MinorLast Reviewed:9/22/2005
Keywords:kbHotfixServer kbQFE kbbug kbfix kbQFE kbsna400sp3fix KB230204
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