DOCUMENT:Q275708  12-JUN-2001  [sna]
TITLE   :TN3270E Bracket Error Because of Race Condition
PRODUCT :Microsoft SNA Server
PROD/VER::4.0,4.0 SP1,4.0 SP2,4.0 SP3
OPER/SYS:
KEYWORDS:sna4 kbsna400sp1 kbsna400sp2 kbsna400sp3 kbSNA400sp4fix kbSNA400PreSP4fix

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

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

SYMPTOMS
========

TN3270(E) clients may intermittently lose their session to the host application.
When the failure occurs, the emulator may display a message indicating that a
"BRACKET ERROR" was encountered; the actual format of the message varies
depending on the TN3270(E) emulator that is being used.

SNA application LUA API traces that are gathered during the failure indicate the
following return codes on the failed session:

   prim_rc=0x1400 (LUA_UNSUCCESSFUL) sec_rc=0x00000320 (LUA_BRACKET)

In addition, the Microsoft Windows NT application event log shows the following
events at the time the failure occurred:

   EventID : 603
   Source : TN3270 Server
   Description : TN3270(E) session with client at xxxx.xxxx.xxxx.xxxx (port xxxx)
   using LU ABCD terminated abnormally because:
   TN3270E Service Error 505
   SNA API verb WRITE failed. Failure described as:
   RUI Write verb has completed with primary rc of Unsuccessful and secondary rc
   of Bracket Protocol Error.
   Explanation : A TN3270(E) client session was terminated abnormally

   EventID : 309
   Source : TN3270 Server
   Description : WRITE failed with LUA_UNSUCESSFUL / LUA_BRACKET for
   xxxx.xxxx.xxxx.xxxx(port xxxx)
   Explanation : An SNA API call failed

CAUSE
=====

The TN3270 server received direction on the session on an RQD chain, and should
have discarded any queued data from the client. Instead, the server attempted to
send the queued data to the host, and subsequently received the bracket error.

RESOLUTION
==========

To resolve this problem, obtain the latest service pack for SNA Server 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



STATUS
======

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

This problem was first corrected in SNA Server 4.0 Service Pack 4.

Additional query words:

======================================================================
Keywords          : sna4 kbsna400sp1 kbsna400sp2 kbsna400sp3 kbSNA400sp4fix kbSNA400PreSP4fix 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ400 kbSNAServ400SP1 kbSNAServ400SP2 kbSNAServ400SP3
Version           : :4.0,4.0 SP1,4.0 SP2,4.0 SP3
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2001.