Microsoft Releases Hotfix Updates to Address Exchange Server Issues
The latest hotfix updates from Microsoft address multiple known issues impacting Exchange servers that have installed the March 2024 security updates. These updates aim to provide improved security measures and resolve previously identified issues.
In addition to addressing the known issues, the optional April 2024 HU (hotfix update) also adds support for ECC certificates and Hybrid Modern Authentication (HMA) for OWA/ECP. However, if you have installed the March 2024 SU (security update) and have not encountered any of the fixed issues or do not require the new features, you can opt to wait for the next Exchange Server SU, which will also include these hotfixes.
The April 2024 HU contains the same security updates as the March 2024 SU, while also providing fixes for any issues caused by the earlier update, as explained by the Exchange Team. If you have not installed the March 2024 SU, you can directly install the April 2024 HU and bypass the March 2024 SU.
This month’s hotfixes from Microsoft have also addressed various issues related to Outlook on the Web (OWA). These include a known issue where download domains were not functioning correctly, leading to issues with inline images and attachments not being downloaded correctly. Another bug causing “We can’t open this document” errors and blocking Microsoft Word document previews in OWA has also been resolved.
The list of fixed issues caused by the March 2024 security updates and addressed in April’s Exchange hotfixes also includes search errors in Outlook cached mode, OwaDeepTestProbe and EacBackEndLogonProbe failing, inability to edit permissions in the ECP, missing unread envelope icons in Outlook, malfunctioning My Templates add-in, and published calendars showing a “This calendar isn’t available” error.
One lingering issue that Microsoft is still working on is related to OWA calendar printing, which currently requires the use of the CTRL+P keyboard shortcut to function properly.
The April 2024 hotfixes are now available for Exchange Server 2019 CU13 and CU14, as well as Exchange Server 2016 CU23.
In January, Microsoft announced that mainstream support for Exchange Server 2019 has ended, although they will continue to release security patches. They will no longer accept requests for bug fixes and Design Change Requests (DCR). Similarly, Exchange Server 2016 reached its mainstream end date in October 2020 but is under extended support until October 2025. Microsoft now provides information and guidance on migrating to Microsoft 365 on their documentation site to assist global admins in making the best migration choice for their organization.