Update 6/13/2025: Please see our new blog post for updated timelines of releases as well as additional details on how to get from current versions of Exchange Server to Exchange Server SE: Upgrading ...
Updated Jun 13, 2025
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I have Exchange 2019 in a Hybrid Office 365 setup, hosted on Windows Server 2019. Is there a supported way of moving to Exchange SE on Windows Server 2025? I would expect that upgrading the OS in place, and then Exchange in place is not supported?
TimGowen, upgrading the underlying OS for an Exchange Server is not now, nor has it ever been, supported (based on numerous posts) but YES, Microsoft knows many people want this feature.
To use Windows 2025, it would seem you would need to do a traditional Exchange server migration to the new 2025 server.
Upgrading Exchange in-place is not normally supported, except in the very specific instance where you are running Exchange Server 2019 CU15. As I understand it, this is because Exchange Server SE RTM will be a binary equivalent to Exchange Server 2019 CU15, except Exchange Server SE RTM:
- will have a different string/branding for the Exchange Server name
- will have a different string/version number
- will contain a different EULA? text file (text file nonetheless)
- will contain any SU for Exchange 2019 CU15 released between now and SE RTM
- If Windows 2025 IS a requirement, you could upgrade your existing Exchange 2019 install to CU15, perform a legacy migration to Exchange 2019 CU15 on the new Windows 2025 server, and then upgrade in-place to Exchange Server SE RTM when it's released.
- If Windows 2025 IS NOT a requirement, you could upgrade your existing Exchange 2019 install to CU15 and then upgrade in-place to Exchange Server SE RTM when it's released.
Note: Exchange 2019 CU15 has been released: Released: 2025 H1 Cumulative Update for Exchange Server | Microsoft Community Hub
I believe this all to be accurate from camping out on Exchange forums for months in preparation for SE.