DOCUMENT:Q172801  02-APR-2000  [sna]
TITLE   :TN3270 Client Session Lost Using PF Keys to Toggle Screens
PRODUCT :Microsoft SNA Server
PROD/VER:WINDOWS:2.11,2.11 SP1,2.11 SP2,3.0,3.0 SP1
OPER/SYS:
KEYWORDS:kbnetwork

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The information in this article applies to:

 - Microsoft SNA Server, versions 2.11, 2.11 SP1, 2.11 SP2, 3.0, 3.0 SP1 
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SYMPTOMS
========

When you rapidly press the PF2 and PF12 keys to toggle between host screens from
a TN3270 client, the client's session is lost and the following error message is
displayed:

   TN3270E Service Error 505
   SNA API verb READ failed. Failure described as:

   RUI read verb has completed with primary rc of Negative Response and
   secondary rc of OK

Within an SNA Server TN3270 internal trace, the RUI_READ request is failing with
primary_rc = 0018 (LUA_NEGATIVE_RESPONSE), followed by the TN3270 server calling
RUI_TERM to terminate the session.

CAUSE
=====

Quick toggling of the PF keys causes a race condition, which results in TN3270
Service receiving LUA_NEGATIVE_RESPONSE error from an RUI function call. The
TN3270 server treats this error as a fatal condition, causing the TN3270 Server
to close the session.

STATUS
======

Microsoft has confirmed this to be a problem in SNA Server versions 2.11, 2.11
Service Pack 1 (SP1), and 2.11 SP2. A supported fix is now available, but has
not been fully regression-tested and should be applied only to systems
experiencing this specific problem. Unless you are severely impacted by this
specific problem, Microsoft recommends that you wait for the next Service Pack
that contains this fix. Contact Microsoft Technical Support for more
information.

Microsoft has confirmed this to be a problem in SNA Server versions 3.0 and 3.0
Service Pack 1 (SP1). This problem was corrected in the latest SNA Server
version 3.0 U.S. Service Pack. For information on obtaining this Service Pack,
query on the following word in the Microsoft Knowledge Base (without the
spaces):

   S E R V P A C K


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

With the fix applied, the TN3270 Server treats this error as a non-fatal
condition and keeps the session active.

Additional query words:

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Keywords          : kbnetwork 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ211 kbSNAServ211SP1 kbSNAServ211SP2 kbSNAServ300SP1
Version           : WINDOWS:2.11,2.11 SP1,2.11 SP2,3.0,3.0 SP1
Issue type        : kbbug
Solution Type     : kbfix

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