TN5250 Event ID 16 Error Causing APPC Session To Fail

• Microsoft SNA Server, versions 3.0, 3.0 SP1, 3.0 SP2, and 4.0

SYMPTOMS

In some situations, such as performing a screen save from a TN5250 session to the AS400, the APPC session fails (the AS/400 rejects one of the messages) and an Event ID 16 is logged from the TN5250 Service on the SNA Server computer with the following text:

   The SNA TN5250 Service detected an unexpected passthrough parameter data
   area flag from the client at <data>.

   The client should not generate this information and it has been
   suppressed. Please verify that the client software has all fix updates
   applied.

CAUSE

In some cases, the data flow comes across two socket calls. The TN5250 Service is incorrectly handling the second call, causing the problem to occur.

STATUS

Microsoft has confirmed this to be a problem in SNA Server 3.0 (all service packs) and SNA Server 4.0. A supported fix is now available for SNA Server 4.0, 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 Product Support Services for more information.

MORE INFORMATION

With the update applied, the TN5250 Service functions correctly in this situation.

Keywords          : snaappc snatn5250
Version           : WINDOWS:3.0,3.0SP1,3.0SP2,4.0
Platform          : WINDOWS
Issue type        : kbbug
Solution Type     : kbfix