(Updated 1/26 to adjust Windows Server entries and links)
Microsoft released today a resolution for an issue observed after installing the January 2026 Windows security update. This issue may cause applications that open or save files stored in cloud‑backed locations to become unresponsive or display errors. Some installations of Outlook may also become unresponsive and fail to open when PST files are stored in cloud‑backed storage such as OneDrive.
An out-of-band (OOB) update was released today, January 24, 2026, to address this issue. This cumulative update includes all protections and improvements from the January 2026 Windows security update released January 13, 2026, as well as from the OOB update released on January 17, 2026 (which introduced fixes for two known issues: remote desktop connections and hibernation failures).
This OOB update is available through Windows Update for Windows 11 devices running the updates released this month. To install it, open Settings > Windows Update, and select Download and install. Note that this update will show up in Windows Update only if you have installed one of the updates released in January that caused this issue. Some devices may install the update automatically. For supported versions of Windows Server and Windows 10, the OOB update is available from the Microsoft Update Catalog. Refer to the KB articles below for detailed information and installation steps.
- Windows 11, versions 25H2 and 24H2: KB5078127
- Windows 11 Enterprise versions 25H2 and 24H2: Hotpatch KB5078167
- Windows 11, version 23H2: KB5078132
- Windows 10 ESU (22H2) and Windows 10 Enterprise LTSC 2021: KB5078129
- Windows Server 2025: KB5078135
- Windows Server, version 23H2: KB5078133
- Windows Server 2022: KB5078136
- Windows Server 2022 Datacenter: Azure Edition: Hotpatch KB5078238
- Windows Server 2019 and Windows 10 Enterprise LTSC 2019: KB5078131
IT administrators using Microsoft Intune or Windows Autopatch should follow the guidance below for installing the OOB update via Windows Update.