SNA Server: Windows NT Client Loses Session To Server

• Microsoft Windows NT Workstation version 3.5
• Microsoft Windows NT Server version 3.5
• Microsoft SNA Server for Windows NT, version 2.1

SYMPTOMS

When you close an SNA Server 5250 (or APPC) session on a Windows NT 3.5 computer, any other SNA applications with a connection to the server lose their session. As a result:

• If SNA Admin is also running on the same machine, and the 5250 session is disconnected. SNA Admin may also lose its connection to SNA Server, causing an SNA Server Admin Error.

  NOTE: 5250 emulators also use the SNA Server APPC interface.

• The Windows NT system event log includes the following error (for each time the user disconnected their 5250 session), if TCP/IP is being used:

        Event: 2012
        Source: Srv
        Description: The server has encountered a network error.
  

• Within an internal SNA Server client trace, the named pipe session fails with rc=59 (An unexpected network error occurred).
• Any other APPC applications with sessions against the same SNA Server receive the following error:

        primary return code = F003 = AP_COMM_SUBSYSTEM_ABENDED
  

  This error returned by SNA Server when its client-server LAN session is lost.

CAUSE

If a Windows NT process has a pending write request on a named pipe and then calls ExitProcess() before the write completes, all other applications connected to the same server pipe fail with error 59 (unexpected pipe close).

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 3.5. This problem has been corrected in the latest U.S. Service Pack for Windows NT version 3.5. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K