Microsoft KB Archive/175778

= Invalid Page Fault in Wappc32.dll Using WinAPPCSetBlockingHook =

Article ID: 175778

Article Last Modified on 9/22/2005

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APPLIES TO


 * Microsoft SNA Server 3.0
 * Microsoft SNA Server 2.11 Service Pack 1
 * Microsoft SNA Server 2.11 Service Pack 2
 * Microsoft SNA Server 3.0 Service Pack 4
 * Microsoft SNA Server 4.0
 * Microsoft SNA Server 3.0 Service Pack 2

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This article was previously published under Q175778



SYMPTOMS
A 32-bit APPC application that initiates multiple conversations and uses the WinAPPCSetBlockingHook call causes a general protection fault (GP fault) in Wappc32.dll on a computer running Windows 95 and using the SNA Server Client for Windows 95. The GP fault will be similar to the following:

This program has performed an illegal operation and will be shut down.

If the problem persists, contact the program vendor.

 caused an invalid page fault in module WAPPC32.DLL at.

Registers:

..data omitted..



CAUSE
The 32-bit APPC library does not correctly handle the case where the WinAPPCSetBlockingHook call returns FALSE on multiple threads.



WORKAROUND
If the WinAPPCSetBlockingHook call is being used to cancel one conversation when the MC_ALLOCATE takes too long. The application should call WinAPPCCancelBlockingCall from within the WinAPPCSetBlockingHook call. If this is done, the WinAPPCSetBlockingHook call would continue to return TRUE instead of FALSE. Another alternative is to have the application use the Asynchronous APPC API and the WinAPPCCancelAsyncRequest call.

Please refer to the SNA Server "APPC Programmer's Guide" for more details on the APPC functions mentioned in this article.



STATUS
Microsoft has confirmed this to be a problem in SNA Server versions 2.11, 2.11 Service Pack 1, 2.11 Service Pack 2, 3.0, 3.0 Service Pack 1, 3.0 Service Pack 2.

The 32-bit APPC library has been updated to correctly handle cases where a WinAPPCSetBlockingHook call returns FALSE. The updated module is Wappc32.dll.

This problem was corrected in the latest SNA Server version 3.0 U.S. Service Pack. For information on obtaining this Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K

A supported fix for SNA Server version 2.11 is now available, 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 Technical Support for more information.

Additional query words: Application Exception AE

Keywords: kbbug kbfix kbqfe kbhotfixserver KB175778

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