DOCUMENT:Q182265  02-APR-2000  [sna]
TITLE   :APPC Display Call Fails With AP_STATE_CHECK (Primary_rc = 0002)
PRODUCT :Microsoft SNA Server
PROD/VER:WINDOWS:3.0,3.0 SP1,3.0 SP2,4.0
OPER/SYS:
KEYWORDS:kbnetwork

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The information in this article applies to:

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

Occasionally, the APPC DISPLAY function will fail with the following error:

   primary_rc = 0x0002 (AP_STATE_CHECK)
   secondary_rc = 0x00000000

This problem seems to occur when two separate DISPLAY calls are made at the same
time from two different threads of the same APPC program.

CAUSE
=====

Although the APPC DISPLAY function is implemented in a thread-safe manner, it
does not properly handle unsolicited status messages received from the SNA
Server, which could cause AP_STATE_CHECK to be returned in error. This problem
is not related to issuing separate DISPLAY calls from different threads.

STATUS
======

Microsoft has confirmed this to be a problem in SNA Server 3.0, 3.0 Service Pack
1 (SP1), 3.0 SP2, and 4.0. We are researching this problem in SNA Server version
3.0 and will post new information here in the Microsoft Knowledge Base as it
becomes available.

This problem was corrected in the latest SNA Server version 4.0 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



Additional query words:

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Keywords          : kbnetwork 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ400 kbSNAServ300SP1 kbSNAServ300SP2
Version           : WINDOWS:3.0,3.0 SP1,3.0 SP2,4.0
Issue type        : kbbug
Solution Type     : kbfix

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