When running a hybrid deployment or when using Exchange Online Archiving in combination with Exchange on-premises, make sure you run the latest CU or one version older (i.e. Exchange 2013 CU23, Exchange 2016 CU18/CU19 or Exchange 2019 CU7/CU8)
No schema changes in these CUs but there are changes to AD, so make sure you run the Setup.exe /PrepareAD command
And as always, test thoroughly in your lab environment, and when deploying make sure your servers are in maintenance mode (especially the DAG).
During an upgrade of an Exchange 2013 SP1 multi-role server to Exchange 2013 CU8 the upgrade crashed, apparantly on a strange Receive Connector configuration since the following error message was raised:
The values that you specified for the Bindings and RemoteIPRanges parameters conflict with the settings on Receive connector ” SERVER1\Relay Connector SERVER1″. Receive connectors assigned to different Transport roles on a single server must listen on unique local IP address & port bindings.
On March 17 Microsoft released the 8th Cumulative Update for Exchange Server 2013, 98 days after the release of CU7 which is nicely in line with the quarterly release cadence of Cumulative Updates. This Cumulative Update is called CU8, not a word about Service Pack 2, so SP1 still continues to be the officially supported Service Pack.
There are some new features in CU8 that are worth noticing.
With CU8 there are improvements for mobile clients in a Hybrid Configuration. When a Mailbox is moved the Outlook client will automatically detect and reconfigure accordingly. This was not the case with Mobile clients. This behavior has changed in CU8. When a mobile client connects the local Exchange server and the Mailbox is moved to Exchange Online an additional check for the TargetOWAUrl on the Organization Relationship object is performed. This will return an HTTP/451 redirect to the mobile client which in turn will be redirected to this new URL. This feature will be available to all EAS compatible devices that can handle the HTTP/451 redirect option. Unfortunately this feature is only available for onboarding customers (i.e. to Office 365) and not for offboarding (from Office 365) customers.
There an improved migration for Public Folders migration, now supporting batch migrations. This is faster (supports multiple jobs), more reliable and provides an easier migration management.
CU8 supports viewing calendar and contact types of modern Public Folders in OWA