Symptoms
An SNA Server 4.0 system may experience an application exception in theSnaservr.exe file in function SNPUPUTI when a PU PassThrough connection isconfigured to use Format 0 XIDs.
When this occurs, a Drwtsn32.log file is generated in the Windows NTdirectory. The Drwtsn32.log file will contain an entry similar to thefollowing:

Application exception occurred:App: snaservr.exe (pid=<process id>)When: <date> @ <time>Exception number: c0000005 (access violation) function: snpuputi0100a65a 8d4e06leaecx,[esi+0x6] ds:014aea06=????????0100a65d 2bd3subedx,ebx0100a65f 0fbfdfmovsxebx,di0100a662 3bdacmpebx,edx0100a664 7e27jlesnpuputi+0×4d (0100a68d)0100a666 85f6testesi,esi0100a668 7427jzsnpuputi+0×51 (0100a691)0100a66a 668b00movax,[eax] ds:01d0fff7=00000100a66d 8b36movesi,[esi] ds:00000000=????????0100a66f 662b01subax,[ecx]ds:01d09d76=0013fault ->0100a672 0fbf5604 movsxedx,word ptr [esi+0x4] ds:014aea07=????0100a676 0fbf5e06movsxebx,word ptr [esi+0x6] ds:014aea07=????0100a67a 8d7c07ffleaedi,[edi+eax-0x1] ds:031be9fe=????????0100a67e 8d4604leaeax,[esi+0x4] ds:014aea06=????????0100a681 8d4e06leaecx,[esi+0x6] ds:014aea06=????????0100a684 2bdasubebx,edx0100a686 0fbfd7movsxedx,di0100a689 3bd3cmpedx,ebx0100a68b 7fd9jgsnpuputi+0×26 (0100a666)0100a68d 85f6testesi,esi0100a68f 750fjnzsnpuputi+0×60 (0100a6a0)0100a691 55pushebp*—-> Stack Back Trace <—-*FramePtr ReturnAd Param#1Param#2Param#3Param#4 Function Name 00dafeec 01041647 01d09d70 0000001a 00000901 01180013 snaservr!snpuputi(FPO: [EBP 0x01d09d70] [3,0,4]) In addition, SNA Server logs an Event 624 in the Windows NT ApplicationEvent log similar to the following:

Creating dump file C:\SNA\traces\snadump.log for Snaservr.exeEXPLANATIONA process (Snaservr.exe) ended abnormally due to a protectionviolation or similar condition and a dump file Snadump.log has beencreated that contains information about the state of the process atthe time of the exception. Register information is contained in yourWindows NT root directory in the file Drwtsn32.log. NOTE: This can only occur when SNA Server is configured to use PUPassThrough connections and one of these connections is configured to useFormat 0 XIDs in the connection properties under the System Identificationtab.
Resolution
The application exception is caused when SNA Server attempts to forward aFormat 3 XID received on one PU PassThrough connection to its partner PUPassThrough connection that is configured to use Format 0 XIDs.