DOCUMENT:Q195469  20-MAY-2002  [winnt]
TITLE   :STOP 0xEFFFFFFF Exception in OLE Servers with Multiple Clients
PRODUCT :Microsoft Windows NT
PROD/VER:WinNT:4.0
OPER/SYS:
KEYWORDS:kbWinNT400sp5fix

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Windows NT Workstation version 4.0 
 - Microsoft Windows NT Server version 4.0 
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SYMPTOMS
========

When multiple clients are concurrently accessing an out of process COM server,
client calls may fail unexpectedly. Debugging the server during such failures
shows that the server is throwing exception 0xEFFFFFFF.

Recognizing this problem can be difficult because both the client and the server
applications may continue running. In particular, this exception does not
directly result in causing of the server or the client to stop responding (hang)
or a crash.

Rather, the server simply returns a failure to the client. Whether the client
continues functioning correctly after such a failure will depend entirely on how
the client software is written. Well behaved client applications may silently
retry the operation or log an error without being otherwise adversely affected.
Clients that do not take care to check the return status of their function calls
may experience access violations or other fatal errors.

To confirm whether this problem is the cause of a specific failure, it is
necessary to debug the server application, set the debugger to break on this
exception, and compare the resultant stack to the one below:

   RPCRT4! RpcRaiseException@4 + 49 bytes
   OLE32! ThreadInvoke(struct _RPC_MESSAGE *) + 524 bytes
   RPCRT4! DispatchToStubInC@12 + 52 bytes
   RPCRT4! RPC_INTERFACE::DispatchToStubWorker(struct _RPC_MESSAGE *,
                unsigned int,long *) + 292 bytes
   RPCRT4! RPC_INTERFACE::DispatchToStub(struct _RPC_MESSAGE *,
                unsigned int,long *) + 93 bytes
   RPCRT4! RPC_INTERFACE::DispatchToStubWithObject(struct _RPC_MESSAGE *,
                class RPC_UUID *,unsigned int,long *) + 176 bytes
   RPCRT4! WMSG_SASSOCIATION::DealWithRequestMessage(union _WMSG_MESSAGE *,
                union _WMSG_MESSAGE *,struct _RPC_MESSAGE *,
                class WMSG_SBINDING * *,unsigned int,int,int,int) + 826
                bytes
   RPCRT4! WMSG_ADDRESS::HandleRequest(union _WMSG_MESSAGE *,
                class WMSG_SASSOCIATION *,struct _RPC_MESSAGE *,
                class WMSG_ENDPOINT *,int,int) + 146 bytes
   RPCRT4! WMSG_ADDRESS::DealWithWMSGRequest(union _WMSG_MESSAGE *,
                class WMSG_ENDPOINT * *,struct HWND__ * *,
                class WMSG_ASSOCIATION *,union _WMSG_MESSAGE * *) + 734
                bytes
   RPCRT4! WMSG_ADDRESS::ReceiveLotsaCalls(void) + 837 bytes
   RPCRT4! RecvLotsaCallsWrapper(class WMSG_ADDRESS *) + 9 bytes
   RPCRT4! BaseCachedThreadRoutine(class CACHED_THREAD *) + 156 bytes
   RPCRT4! ThreadStartRoutine(class THREAD *) + 23 bytes
   KERNEL32! 77f04f44()

CAUSE
=====

The OLE functions handling typelib marshaling are not completely multithread
safe, resulting in a narrow window of opportunity for the exception to take
place if two or more clients are making concurrent calls to the server.

RESOLUTION
==========

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or
the individual software update. For information on obtaining the latest service
pack, please go to:

 - http://www.microsoft.com/windows/servicepacks/

-or-

 - Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack

For information on obtaining the individual software update, contact Microsoft
Product Support Services. For a complete list of Microsoft Product Support
Services phone numbers and information on support costs, please go to the
following address on the World Wide Web:

   http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS


STATUS
======

Microsoft has confirmed this to be a problem in Windows NT version 4.0. This
problem was first corrected in Windows NT 4.0 Service Pack 5.

Additional query words: 4.00 object linking embedding com dcom distributed
======================================================================
Keywords          : kbWinNT400sp5fix 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400
Version           : WinNT:4.0
Hardware          : ALPHA x86
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

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