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Users in an Exchange Server 2013 environment cannot obtain free/busy information in a cross-forest setup when the number of AvailabilityAddressSpace objects exceeds 100. In this situation, the following error is returned:

Failed to get freebusy response for user:EmailAddress = <>, Attendee Type = Required, Exclude Conflicts = False. Message: Unable to send cross-forest request for mailbox <UserName> because of invalid configuration., inner exception: Microsoft.Exchange.InfoWorker.Common.Availability.AddressSpaceNotFoundException: Configuration information for forest/domain could not be found in Active Directory.
at Microsoft.Exchange.InfoWorker.Common.Availability.TargetForestConfigurationCache.FindByDomain(OrganizationId organizationId, String domainName)
at Microsoft.Exchange.InfoWorker.Common.Availability.QueryGenerator.GetTargetForestConfiguration(EmailAddress emailAddress)


This problem occurs because 100 was hard-coded as the maximum number of AvailabilityAddressSpace objects that can be read from Active Directory Domain Services (AD DS) in Exchange Server 2013.


To resolve this issue, installĀ Cumulative Update 8 for Exchange Server 2013.

More Information

For more information about this issue, see Add-AvailabilityAddressSpace.


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

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