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Q326224: FIX: SNA Applications That Use SSO May Stop Responding

Article: Q326224
Product(s): Microsoft SNA Server
Version(s): 4.0,4.0 SP1,4.0 SP2,4.0 SP3,4.0 SP4
Operating System(s): 
Keyword(s): sna4 kbsna400sp1 kbsna400sp2 kbsna400sp3 kbhis2000 kbhis2000bug kbsna400sp4
Last Modified: 30-JUL-2002

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The information in this article applies to:

- Microsoft SNA Server, versions 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3, 4.0 SP4 
- Microsoft Host Integration Server 2000 
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SYMPTOMS
========

An SNA application, such as a 3270 or 5250 emulator, that is configured to use
Single Sign-On (SSO), may stop responding (hang) when the application tries to
connect to a host session. When this problem occurs, the 3270 or 5250 emulator
typically shows a blank display window after the connection to the host session
is initiated.

SNA applications that have existing host sessions are not affected when this
problem occurs.

CAUSE
=====

If a Host Account Cache (HAC) database that is being used by the SNA Server
service for SSO account lookups becomes unavailable, a deadlock can occur that
prevents the SNA Server service from locating another HAC database.

SNA applications that use SSO stop responding while the SNA Server service is in
this deadlock state because the account lookups cannot be completed.

RESOLUTION
==========

SNA Server 4.0:

A supported fix is now available from Microsoft, but it is only intended to
correct the problem that is described in this article. Only apply it to systems
that are experiencing this specific problem. This fix may receive additional
testing. Therefore, if you are not severely affected by this problem, Microsoft
recommends that you wait for the next Microsoft SNA Server version 4.0 service
pack that contains this fix.

To resolve this problem immediately, 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 has the file attributes (or later) that are
listed in the following table. The dates and times for these files are listed in
coordinated universal time (UTC). When you view the file information, it is
converted to local time. To find the difference between UTC and local time, use
the Time Zone tab in the Date and Time tool in Control Panel.

  Date         Time   Version     Size      File name
  ---------------------------------------------------------
  15-Jul-2002  12:32  4.0.0.606   138,848   Snarpc.dll       

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



Host Integration Server 2000:

No fix is available for this problem in Host Integration Server 2000 at this
time.


WORKAROUND
==========

To resolve this problem, restart the SNA Server service on the SNA Server or
Host Integration Server 2000 through which the SNA application is trying to
connect.

STATUS
======

SNA Server 4.0:

Microsoft has confirmed that this is a problem in Microsoft SNA Server version
4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3, 4.0 SP4.

Host Integration Server 2000:

Microsoft has confirmed that this is a problem in Microsoft Host Integration
Server 2000.



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

For additional information about how the SNA Server service locates a Host
Account Cache database to use for account lookups, click the article number
below to view the article in the Microsoft Knowledge Base:

  Q248479 Host Account Database Location for Single Sign-On

If the HAC database that is being used for account lookups becomes unavailable,
the SNA Server service detects this, and then contacts the master HAC database
to locate another HAC database to use for account lookups.


For additional information about other issues related to SNA applications and SSO
problems, click the article numbers below to view the articles in the Microsoft
Knowledge Base:

  Q321245 3270 Emulators and LUA Applications Stop Responding When They Use the
  Single Sign-On Feature

  Q319419 Unable to Log On to Host Computer When You Use 3270 Single Sign-On

  Q313202 SSO Fails If Attach Message Does Not Contain LUWID or Other Subfield

Additional query words:

======================================================================
Keywords          : sna4 kbsna400sp1 kbsna400sp2 kbsna400sp3 kbhis2000 kbhis2000bug kbsna400sp4 
Technology        : kbAudDeveloper kbSNAServSearch kbHostIntegServ2000 kbSNAServ400 kbSNAServ400SP1 kbSNAServ400SP2 kbSNAServ400SP3 kbSNAServ400SP4
Version           : :4.0,4.0 SP1,4.0 SP2,4.0 SP3,4.0 SP4
Issue type        : kbbug
Solution Type     : kbfix

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