Released: 2024 H1 Cumulative Update for Exchange Server

Ron Ron no schema changes will be done if you upgrade from CU13. See this documentation: https://learn.microsoft.com/en-us/exchange/plan-and-deploy/active-directory/ad-schema-changes?view=exchserver-2019

This is what happens if you do the domain preparation: https://learn.microsoft.com/en-us/exchange/plan-and-deploy/active-directory/ad-changes?view=exchserver-2019#prepare-active-directory-domains .

As you can see in this table: https://learn.microsoft.com/en-us/exchange/plan-and-deploy/prepare-ad-and-domains?view=exchserver-2019#exchange-2019-active-directory-versions there is no change of the objectVersion (Default) version number compared to CU13. This means that no domain preparation is needed (except if you've added additional domains to your AD which should be enabled to work with Exchange Server).

The objectVersion (Configuration) was raised compared to CU13, which means that prepare AD is required (otherwise setup will fail). We don't have a documentation that describes the changes what prepare AD does. It's hard (nearly impossible) to say what exactly will be done in your environment. This is because prepare AD will correct anything that is misconfigured/unexpected configured (e.g., the AD admin makes a change to something that is used by Exchange, prepare AD will detect and configure it to the expected configuration).

See https://learn.microsoft.com/en-us/exchange/plan-and-deploy/active-directory/ad-changes?view=exchserver-2019#prepare-active-directory-containers-objects-and-other-items for more information about prepare AD