This article has been archived. It is offered "as is" and will no longer be updated.
When multiple clients are concurrently accessing an out of process COMserver, client calls may fail unexpectedly. Debugging the server duringsuch failures shows that the server is throwing exception 0xEFFFFFFF.
Recognizing this problem can be difficult because both the client and theserver applications may continue running. In particular, this exceptiondoes not directly result in causing of the server or the client to stopresponding (hang) or a crash.
Rather, the server simply returns a failure to the client. Whether theclient continues functioning correctly after such a failure will dependentirely on how the client software is written. Well behaved clientapplications may silently retry the operation or log an error without beingotherwise adversely affected. Clients that do not take care to check thereturn status of their function calls may experience access violations orother fatal errors.
To confirm whether this problem is the cause of a specific failure, it isnecessary to debug the server application, set the debugger to break onthis exception, and compare the resultant stack to the one below:
The OLE functions handling typelib marshaling are not completelymultithread safe, resulting in a narrow window of opportunity for theexception to take place if two or more clients are making concurrent callsto the server.
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:
152734 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: