Microsoft KB Archive/166529

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Article ID: 166529

Article Last Modified on 6/5/2006


  • Microsoft SNA Server 3.0 Service Pack 4
  • Microsoft SNA Server 4.0
  • Microsoft SNA Server 3.0 Service Pack 2
  • Microsoft SNA Server 4.0

This article was previously published under Q166529


APPC applications and 5250 emulators may appear to hang when trying to connect to a SNA Server, version 3.0 (including all SPs) or 4.0 system.

APPC applications and 5250 emulators may appear to hang when trying to connect to a SNA Server, version 3.0 or 3.0 Service Pack 1 (SP1) system.

After starting a 5250 session and entering an AS/400 userid and password in the AS/400 logon dialogue, the 5250 session will continue to display a blank screen and will not display the AS/400 signon screen. The session may eventually display an error similar to the following:

Could not connect to remote host.


This is the error that was displayed when using the 5250 Applet that is included with SNA Server when QPCSUPP was configured as the Implicit Incoming Mode in SNA Server Manager. It took several minutes before the error was displayed. The error message may be different depending on the emulator that is being used.

For other APPC applications, a SNA Server LU 6.2 Message trace may show that the SNA Server nevers responds to the "Open LU62 Request" that it receives from the APPC DLL on the client running the application.

If you are using dependent APPC LUs, this message may appear in the Application Event Log:

Event ID 7

APPC session activation failure: LU inactive
   Connection   = SUNGARD 
   LU alias     = SUNGARD 
   PLU alias    = WNWCI52D
   Mode name    = PA62TKNU
   LU address   =


This problem is caused if the Remote APPC LU defined in SNA Server 3.0 is configured to use an Implicit Incoming Mode that matches the APPC Mode that the application will be using. For example, the problem would occur if the Implicit Incoming Mode was set to APPCMODE and the APPC application was defined to use this mode.

The Implicit Incoming Mode is configured on the Options tab of the Remote APPC LU's property page in SNA Server Manager.


An Implicit Incoming Mode is used to define the properties to use when SNA Server receives a request to start an APPC session when an incoming APPC Allocate specifies a null Mode name or if the specified Mode name is not recognized by SNA Server.


The workaround is to change the Implicit Incoming Mode setting for Remote APPC LUs to either <None> or to a Mode name that the APPC/5250 applications are not actually using.


Microsoft has confirmed this to be a problem in SNA Server version 3.0, 3.0 SP1, 3.0 SP2, and 4.0. This problem was corrected in the latest SNA Server versions 3.0 and 4.0 U.S. Service Packs. For information on obtaining these Service Packs, query on the following word in the Microsoft Knowledge Base (without the spaces):


Additional query words: hang black

Keywords: kbqfe kbhotfixserver KB166529