Symptoms
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 = <>SMTP:user@domain.com, Attendee Type = Required, Exclude Conflicts = False. Message: Unable to send cross-forest request for mailbox <UserName>SMTP:user@domain.com because of invalid configuration., inner exception: Microsoft.Exchange.InfoWorker.Common.Availability.AddressSpaceNotFoundException: Configuration information for forest/domain domain.com 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)
Cause
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.
Resolution
To resolve this issue, install Cumulative Update 8 for Exchange Server 2013.
More Information
For more information about this issue, see Add-AvailabilityAddressSpace.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
