SYMPTOMS
The Microsoft SNA Server APPC Programmer's Reference documents the
following reason for a primary return code of F002 (AP_TP_BUSY) error:
F002 AP_TP_BUSY
The Local TP has issued a call to APPC while APPC was processing another
call for the same TP. This may occur if the local TP has multiple
threads, and more than one thread is issuing APPC calls using the same
tp_id.
However, this is not the only possible cause of this error when running the
Windows 3.x client. The SNA Server Windows 3.x APPC interface also returns
AP_TP_BUSY (primary return code = F002) to an application if it calls into
the APPC interface from a Windows procedure from SendMessage().
Applications that talk over the CPIC interface may also encounter this
problem because the CPIC API communicates over the APPC API. If this APPC
error is returned to the CPIC interface as a result of a CMINIT call, CPIC
returns Error 20 (product specific error) to the application. To see if
this error is occurring, SNA Server Windows 3.x CPIC and APPC API tracing
must be enabled. For additional information, please see the following
article(s) in the Microsoft Knowledge Base:
123256 Enabling SNA Server Windows 3.x Client Traces
Some third party applications require do not run reliably on the SNA Server
Windows 3.x client software unless the TP_BUSY check is disabled. Wall Data
Rumba AS/400 Shared Folders requires that the TP_BUSY check is disabled.
RESOLUTION
Using the SNA Server 2.11 Windows 3.x client software, the following
parameter can be set in the [wnap] section of WIN.INI file to disable this
SendMessage check:
The SNA Server Windows client process (WNAP) must be stopped and started
to enable this change.
WARNING: This parameter should be used with caution, since it can lead to
deadlocks from within Windows, depending on the other Windows applications
that are running on the computer.