Microsoft silently released Exchange 2013 CU10 on September 15th 2015, right on track with their quarterly cadence, and as expected. There are no new features in this Cumulative Update, but besides a lot of hotfixes there’s also a change to RBAC which require changes to the Configuration Partition in Active Directory.
So, no changes to the Active Directory Schema, but you have to run Setup.exe /PrepareAD /IAcceptExchangeServerLicenseTerms before you start the actual setup. Please note that you have to do this, even if you run the GUI version of setup. If you omit this step the changes won’t be applied to Active Directory. As a result, the RBAC changes might not be available after your upgrade. A similar issue happened with CU9 as written down in this blog post MessageCopyForSentAsEnabled and MessageCopyForSendOnBehalfEnabled not available in CU9.
Before installing Exchange 2013 CU10 in your production environment I recommend testing it thoroughly in a lab environment. The last couple of CU’s have been pretty successful without too many issues, but there might be specific issues in your own organization that Microsoft is unaware of.
When upgrading DAG members please remember you disable all the Exchange server components as explained in my blog about deploying Exchange 2013 CU9.
You can download CU10 here, and the CU10 Language packs here. A complete list of issues resolved can be found in Knowledge Base Article KB3078678.
At the same time Microsoft released released Exchange Server 2010 Service Pack 3 Update Rollup 11 (KB3078674).
When Exchange 2016 is released in the (near) future, you will need Exchange 2013 CU10 or Exchange Server 2010 SP3 Update Rollup 11 for coexistence. This will be hardcoded in the product, so if you’re planning to deploy Exchange 2016 in the future you have to install these version.
Also, when you’re running an Exchange 2013 Hybrid scenario with Office 365 you have to use the latest version, so in this case Exchange 2013 CU10 is mandatory.