Microsoft releases several Hotfix Updates (HUs) for Microsoft Exchange Server on May 29, 2025. It includes fixes for non-security issues and introduces new features. These fixes and features will also be included in later Cumulative Updates for Exchange Server 2019.
Note: This update also includes all the updates that were included in the November 2024 security updates for Exchange Server.
Exchange Server Hotfix Updates
The May 2025 HU is available for the following builds of Exchange Server:
Read more on how to Install Exchange Hotfix/Security Update.
If you are not on these Exchange Server CU versions, please update right now and apply the above patch.
Read more on how to Install Exchange Cumulative Update.
Issues fixed in this update
Note: Microsoft is retiring a feature in Exchange Online that previously enabled who have a primary mailbox that’s hosted on Exchange Server (on-premises) to access their archive mailbox, hosted in Exchange Online, through Outlook on the Web (OWA). For more information: Changes in OWA interface because of cloud archive mailbox retirement.
FAQs
We installed the last Security Update. Should we install the later Hotfix Update?
Exchange Server HUs are optional updates, but they might introduce features or fixes that your organization can benefit from.
We did not yet install the earlier Security Update. Do we have to install the last available SU first before installing the later HU?
All of Exchange updates (HUs or SUs) are cumulative. Therefore, a newer HU will contain all the changes that a previous, older SU has. If you have not installed the older SU yet, you can install the newer HU directly and skip the older SU.
Our Exchange servers update automatically through Windows / Microsoft Update. Will our servers automatically install the HU update?
HUs will appear as an optional update for your servers. The update will also be available on the Microsoft Update Catalog after a few days of delay.
Will the new features and fixes released in the HU also be rolled into future updates, or must we install this specific HU to get them?
Content of this HU will be included in subsequent updates for Exchange Server.
Can HUs be uninstalled (if the need arises)?
Yes. HUs, like SUs, can be uninstalled.