[German]A short reminder for administrators of Exchange 2016 and Exchange 2019 installs, that should and should be on the radar since months. In October 2025, both Microsoft Exchange Server 2016 and Microsoft Exchange Server 2019 will no longer be supported. Microsoft has recently drawn attention to this fact and outlined migration paths as offered.
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Reminder of the end of support
Microsoft's announcement was made on January 15, 2024 in the T-9 months: Exchange Server 2016 and Exchange Server 2019 End of Support, and it was pointed out that October 14, 2025 is the dead line for support.
In the article, the Exchange team points out that there are only 9 months until the products Microsoft Exchange Server 2016 and Microsoft Exchange Server 2019 are replaced. After October 14, 2025, Microsoft will no longer offer technical support for problems that may occur with Exchange 2016 or Exchange 2019.
Redmond explicitly lists technical support for issues that arise, fixes for discovered bugs that may affect the stability and usability of Exchange Server, and security fixes for discovered vulnerabilities that make Exchange Server vulnerable as discontinued. Updates for time zone adjustments will no longer be made.
Customers who continue to operate installations of Exchange 2016 and Exchange 2019 are therefore faced with the problem that there will no longer be any support in the event of problems, even if the systems in question continue to run after October 14, 2025.
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Microsoft recommendations for migration
Due to the imminent end of support and potential future security risks, Microsoft recommends that customers take urgent action now and plan or start a migration to successor solutions.
Microsoft's recommendation for its customers is to migrate to Exchange Online . The alternative is to prepare the organization for an upgrade to the Exchange Server Subscription Edition (SE). This is due to be available at the beginning of the second half of 2025 – which is a very tight deadline.
What does this mean for Exchange 2016 users?
Back in August 2024, Microsoft provided information on the replacement of Exchange 2016 (see Microsoft on the "decommissioning"; of Microsoft Exchange 2016).
If you are still using Microsoft Exchange 2016, Microsoft recommends that you perform a legacy upgrade to Exchange 2019 now. An in-place upgrade to Exchange Server SE will then be possible later as soon as this product is available.
The problem is that a license for Exchange 2019 would then be required. According to Microsoft, it will also be possible to perform a legacy upgrade from Exchange 2016 to Exchange Server SE RTM and skip Exchange 2019 completely. However, since (according to current Microsoft planning) there are less than 4 months between the release of Exchange Server SE and the end of support for Exchange 2016, this could lead to timing issues, depending on the size of the deployment and other factors. An in-place upgrade from Exchange 2016 to Exchange SE will not be available.
This is why Microsoft recommends upgrading to Exchange Server 2019 now and decommissioning existing Exchange 2016 servers in a timely manner. This is the only way to ensure that the switch to Exchange Server SE can take place via an in-place upgrade.
Exchange 2019 enables in-place upgrade
Microsoft suggests with the name Exchange Server SE that it is a new product. Under the hood, however, it is more of a "service pack", which is also noted in the above tweet by Frank Carius. Administrators of Exchange 2019 install this "CU" and switch the product to Exchange Server SE. However, it should be noted that this product requires a new (subscription) license.
It is also still unclear when Microsoft will release CU15 for Exchange 2019, which was announced for January 2025 (see Exchange Server 2019: CU15 delayed until January 2025). Further details on Microsoft's plans can be found in the linked Techcommunity article.
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