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Microsoft KB Archive/170989

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Knowledge Base

Article ID: 170989

Article Last Modified on 7/11/2005


  • Microsoft OLE 4.0, when used with:
    • Microsoft Platform Software Development Kit-January 2000 Edition

This article was previously published under Q170989


Under Windows NT 4.0, no more than 110 methods can be present in an OLE automation dual interface that is remoted via type library marshalling. Some applications, such as Microsoft Word, have automation interfaces containing more than 110 methods. This can cause crashes and other unexpected behavior when a controller invokes an automation method in such a server.

The limit under Windows 95 is 512 methods per dual interface.


This problem is caused by a marshalling bug in the RPC runtime libraries.


The limit on the number of methods in an interface has been increased in the later releases of the RPC libraries.


Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. The limit on the number of interface methods has been increased in Windows NT 4.0 Service Pack 2 (see the MORE INFORMATION section of this article).


Currently the maximum number of methods in an OLE automation dual interface are:

Windows NT 4.0 - 110 methods
Windows NT 4.0 SP2 - 512 methods
Windows NT 4.0 SP3 - 1024 methods
Windows 95 - 512 methods
Windows 98 - 1024 methods
Windows 2000 and later, unlimited

Keywords: kbbug kbfix kboswinnt400sp2fix kbautomation KB170989