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"Invalid user context cookie found in proxy response" error message and an event ID 4999 occur when you use an Exchange 2010 SP2 RU1 CAS server as a proxy to an Exchange 2007 CAS server

Symptoms
Consider the following scenario:
  • You configure a server that is running Microsoft Exchange Server 2010 Service Pack 2 (SP2) as a Client Access server (CAS).
  • The server that is running Exchange Server 2010 SP2 is used as a proxy to a server that is running Microsoft Exchange Server 2007.
  • You install Microsoft Exchange Server 2010 SP2 Update Rollup 1 (RU1) on the proxy server.
In this scenario, the proxy connection fails from the server that is running Exchange Server 2010 SP2 RU1 server to the server that is running Exchange Server 2007. And, you receive an error message that resembles the following:
Invalid user context cookie found in proxy response
Additionally, an event that resembles the following is logged in Event Viewer:

Event ID: 4999
Log Name: Application
Source: MSExchange Common
Task Category: General
Level: Error
Description: Watson report about to be sent for process id: 744, with parameters: E12, c-RTL-AMD64, 14.02.0283.003, OWA, M.E.Clients.Owa, M.E.C.O.C.ProxyUtilities.UpdateProxyUserContextIdFromResponse, M.E.C.O.Core.OwaAsyncOperationException, 413, 14.02.0283.003.

Cause
This issue occurs because of change to the user context cookie in Exchange Server 2010 SP2 RU1.
Resolution
To resolve this issue, download and install Update Rollup 7 for Exchange Server 2007 SP3. For information about how to download and install Update Rollup 7 for Exchange Server 2007 SP3, visit the following Microsoft website:
Workaround
To work around this issue, use redirection instead of using a proxy.
References
For more information about Update Rollup 7 for Exchange Server 2007 SP3, visit the following TechNet website:
Properties

Article ID: 2696649 - Last Review: 06/21/2014 17:19:00 - Revision: 4.0

Microsoft Exchange Server 2007 Service Pack 3

  • kbfix kbprb kbtshoot kbsurveynew KB2696649
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