SNA Server APPC Error: F004 AP_COMM_SUBSYSTEM_NOT_LOADED

• Microsoft SNA Server for Windows NT, versions 2.0, 2.1, 2.11, 2.11 Service Pack 1, and 3.0

SYMPTOMS

When you attempt to start an SNA Server APPC Transaction Program (TP), the following error message appears:

   Primary Return Code = F004 AP_COMM_SUBSYSTEM_NOT_LOADED

   Secondary Return Code = 010000F0

   Secondary Return code = 020000F0

CAUSE

The two secondary return codes appear due to the causes described below. The secondary return codes are documented on page 101 of the SNA Server APPC Programmer's Guide as X'F0000001' and X'F0000002' respectively. Intel processors store double-word values in byte inversed format. Therefore, an application may display the secondary return code as 0x010000F0 or 0x020000F0.

Secondary Return Code = 010000F0

This error occurs when the SNA Server client does not find any active SNA Servers running in the SNA Server domain or subdomain. If there are SNA Servers running, then this can also indicate that the SNA client is unable to receive a "sponsor" connection to an SNA Server in the domain. Specific causes of this problem include the following:

• The SNA Server service is not started on the SNA Server.
• When you run SNA Server 2.11 or greater and no more SNA Server licenses are left (Per Server Reached = Per Server Purchased, or Per Server Purchased is set to 0). To verify the status of the licenses, use License Manager in the Network Administration group.
• The SNA Server client software is unable to connect to the SNA Server over the client-server LAN interface that has been selected. The following are reasons that prevents a LAN session from opening:

      - User does not have permission to connect to the Windows NT Server
        where SNA Server is running.
  

      - If this error occurs on an SNA Server Windows NT client, the SNA
        Server that the client is connected to must have the Windows NT Guest
        account enabled.
  

        SNA Server aware applications, such as the 5250 or 3270 applet, rely
        on the SNA Server client-server interface to create LAN sessions on
        its behalf. If a user logs on to a client (where the SNA Server
        application is running), which does not have permissions to create a
        LAN session with the SNA Server, then this error occurs. If you
        select Microsoft Networking during SNA client installation, connect
        to the IPC$ resource on the server:
  

           \\<SNA_Server_name>\ipc$
  
        If this prompts for a password, there is a user permission problem
        with your Windows NT domain user name and password. If you select
        Microsoft Networking, the SNA Server client relies on the client-side
        redirector to connect to the IPC$ resource through the Windows NT
        Server. For Banyan IP, native TCP/IP and IPX/SPX, the user provides
        the Windows NT user ID, password and Windows NT domain information to
        the SNA Server client software. Then this authenticates the user
        request against the Windows NT Server.
  
        The Otherservers entry is used to append an SNA Server outside the
        client's local Windows NT domain to the client's local service table.
        If the local LU you are attempting to connect to is only defined on
        an Otherservers SNA Server, the user must have the permission to
        create a Windows NT LAN session to that SNA Server. The Windows
        Domain Administrator may want to enable the Guest account on that SNA
        Server because the Otherservers SNA Servers are commonly outside the
        client's local domain.
  
  

• If the SNA Server has two network interface cards (NICs) and TCP/IP sockets are used to connect to the server. For additional information, see the following article in the Microsoft Knowledge Base:

        ARTICLE-ID: Q128986
        TITLE     : Connecting over TCP/IP to SNA Server with Multiple Net
                    Cards
  
  

• In a Windows 3.x or Windows for Workgroups client computer, the SNA client software or network software may encounter memory allocation errors. The following appears in an application internal trace when there is not enough memory to read on a pipe (if Microsoft Networking is selected in the SNA Server client setup):

        47.67 DASYR  03-05 15:23:53  Asynch read failed, pipe handle 11,
        rc = 8
  

  For additional information on how to tune memory on a Windows client, see the following article in the Microsoft Knowledge Base:

        ARTICLE-ID: Q126432
        TITLE     : SNA Server Windows Client Memory Tuning
  
  

Secondary Return code = 020000F0

This error occurs if the local LU alias is not contained within the "LU_Alias" field of the TP_Started APPC verb. For example, if you do not enter a local LU Alias in the SNA Server 5250 Applet, do not default the User record with an appropriate local LU alias in SNA Server Admin Users and Groups window, or do not define the local APPC LU as a member of the default outgoing pool, this error occurs.

NOTE: If you use a CPIC application, the following CPIC error message and the "APPC error F004 020000F0" error message appear:

   Error 20 (CM_PRODUCT_SPECIFIC_ERROR)

   ARTICLE-ID: Q132720
   TITLE     : SNA Server CPIC Allocate Error 20
               (CM_PRODUCT_SPECIFIC_ERROR)