Symptoms
Assume that you deploy a mix of servers that run Microsoft Exchange Server 2016, 2013, and 2010. You run the following cmdlet in the Exchange Server 2010 Management Shell (EMS) to remove this server as a proxy endpoint:
Set-ClientAccessServer -Identity <server_name> -IsOutofService $True
Note You can restart the MSExchangeADTopology service and the Internet Information Services (IIS) application pools in Exchange Server 2016 to make sure the change takes effect immediately. To determine whether this change has taken effect, try to access a mailbox that's hosted on Exchange Server 2010 by logging on to OWA. If the logon attempt is unsuccessful, this means that the change has taken effect.
Then, you revert the IsOutofService value to False by running the following cmdlet on the Exchange Server 2010 Client Access server (CAS):
Set-ClientAccessServer -Identity <server_name> -IsOutofService $False
In this case, you expect to log on to your mailbox from OWA without any problem. However, you cannot log on to OWA. Additionally, if you try to log on to OWA from the Exchange Server 2016 environment for a mailbox that exists on Exchange Server 2010, the attempts may continue to be unsuccessful for a day or more.
Cause
This issue occurs because the IsOutofService value is not updated in time by IIS and Microsoft Exchange Active Directory Topology services in the Exchange Server 2016 and 2013 environment.
Resolution
Exchange Server 2016
To resolve this issue, install Cumulative Update 10 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.
Exchange Server 2013
To resolve this issue, install Cumulative Update 21 for Exchange Server 2013 or a later cumulative update for Exchange Server 2013.
Workaround
To work around this issue, restart the Microsoft Exchange Active Directory Topology services and IIS in the Exchange Server 2016 and 2013 environment.
To restart Microsoft Exchange Active Directory Topology services, run the following cmdlet in PowerShell:
Restart-Service -Name MSExchangeADTopology -Force
To restart IIS, click Start, click Run, type IISReset and then click OK.
A Command Prompt window opens and displays the status of the IISReset command. You should read the status at the command prompt to make sure that IIS stops and then restarts.
References
Learn about the terminology that Microsoft uses to describe software updates.
