Event ID 4999 is logged and MSExchangeServicesAppPool crashes in an Exchange Server 2010 environment


The event log resembles the following:

Log Name: Application
Source: MSExchange Common
Date: Date 
Event ID: 4999
Task Category: General
Level: Error
Keywords: Classic
Watson report about to be sent for process id: Process ID, with parameters: E12, TypeVersion Number, WS, unknown, M.E.S.C.E.EwsHttpResponseWireWriter.InternalEndSendResponse, System.NullReferenceException, dda, unknown.
ErrorReportingEnabled: False


This issue occurs because a third-party product disconnects in an unexpected state. This disconnection causes a System.NullReferenceException exception, and that triggers the crash.


To resolve this issue, install Update Rollup 10 for Exchange Server 2010 Service Pack 3.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

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