EDIT 2/10/2025: We have now released Exchange 2019 CU15. Please see this post for more information.
Last December, we announced that we were delaying the release of Exchange Server 2019 CU15 to January 2025 (and consequently, that the CU would be renamed to H1 2025 CU).
Today, we wanted to share what is going on, why CU15 is still not released and share some related news.
Exchange 2019 CU15 release status
We are still not ready to publicly release CU15. Indeed, this is a delay that is unexpected. There are several good reasons why we keep delaying the release:
- Exchange 2019 CU15 is the last CU for Exchange 2019. We have committed to Exchange Server CU15 being the “code equivalent” to Exchange Subscription Edition (SE) RTM release (other than updates released in interim, as well as changed branding and EULA). Therefore, CU15 is the last chance that we have if we want to release any Exchange features before Exchange SE CU1. CU15 does include new features which added complexity to this release.
- As a part of validation of new CU releases, we send them to customers who are enrolled into our TAP program. This is an additional validation of upcoming CUs in “real life” environments. It is through this program that we have received information of some late issues with CU15, and have taken a decision to address them and create a new CU15 build. When we create a new build, we effectively reset the testing process, which adds time to public release.
We are almost ready for the release.
Exchange 2019 CU14 is now supported on Windows Server 2025
Part of the CU15 release validation was ensuring that Exchange CU15 is ready to be installed on Windows Server 2025, so customers can build new servers, on new hardware and OS, in preparation to future in-place upgrade to Exchange SE.
We are happy to announce that both CU14 and CU15 include support for running Exchange Server 2019 on Windows Server 2025 and in organizations that use Active Directory servers that run Windows Server 2025. This means you can install either CU14 or CU15 on brand new hardware with Windows Server 2025, and then upgrade in-place to Exchange Server Subscription Edition (SE) to get the maximum supported product lifecycle out of the server. We previously mentioned that this support would come to CU15, but we also validated CU14 for this scenario to ease your migrations to the latest version of Windows Server.
The path forward
We acknowledge that CU15 delay has been frustrating. We are working to make the release ready. It is coming! Please continue working on preparing your organizations for Exchange SE, by migrating to Exchange 2019 today. Migrating today gives you time, and you should not wait for Exchange SE RTM to join the organization and move mailboxes only then.
- We are not changing any of our already announced lifecycle dates.
- This has no effect on the timing of the RTM release of Exchange Server SE, which is still expected in early H2 of CY25.
- Our guidance for all customers remains the same: get to Exchange Server 2019, install the latest update, and upgrade in-place to Exchange Server SE when available.
Exchange Server Team
