The Update BureauKB5078129: Cumulative update for Windows 10, versions 21H2 and 22H2, January 2026. Cloud-file errors and Outlook hangs fixed
Fixes errors affecting some apps that open or save cloud-stored files, including Outlook hangs in certain configurations. Some PCs with Virtual Secure Mode enabled might still restart instead of shutting down; KB5075912 resolves that issue.
Does it affect you? Applies to: Windows 10, version 22H2 devices enrolled in ESU, and Windows 10 Enterprise LTSC 2021, version 21H2.
What changes
Fix 1 change
File System
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Some applications no longer become unresponsive or encounter errors when opening files from or saving files to cloud storage. In certain Outlook setups, the fix also addresses hangs, missing sent items, and previously downloaded emails being downloaded again.1
The Outlook issue affects certain configurations that store PST files on OneDrive. These issues began after Windows updates released on and after January 13, 2026.
Improvement 1 change
Servicing stack
For: Azure-hosted devices and IT administrators
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The update improves checks used to verify whether a device is hosted on Azure, supporting the installation of future updates on Azure-hosted devices.2
The included SSU uses enhanced logic and an updated certificate chain for Azure-hosting validation. Microsoft recommends installing it before applying additional updates to Azure-hosted devices and ensuring access to the required certificate update domains.
Known issues
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Some devices with Virtual Secure Mode enabled might fail to shut down or hibernate
Some Secure Launch-capable PCs with Virtual Secure Mode (VSM) enabled might restart instead of shutting down or entering hibernation. KB5075912 addresses this issue.3
Resolution Fixed in KB5075912Install KB5075912 (or a later cumulative update) on affected devices. No manual workaround is required after updating.
Technical details
Data sheet · Security · Downloads · Components Click to collapse or expand
Data sheet
- Released
- 2026-01-24
- Classification
- Updates
- Type
- Cumulative update
- Restart
- Required
- Replaces
-
KB5077796, KB5073724, KB5074976, KB5071546
+30 earlier
KB5068781, KB5066791, KB5066198, KB5065429, KB5063842, KB5066188, KB5063709, KB5062649, KB5062554, KB5061087, KB5063159, KB5060533, KB5058481, KB5061979, KB5061768, KB5055612, KB5053643, KB5052077, KB5050081, KB5046714, KB5045594, KB5043131, KB5041582, KB5040525, KB5039299, KB5037849, KB5036979, KB5035941, KB5034843, KB5034203 - Replaced by
- KB5075912
| Version | Build | Channel |
|---|---|---|
| 21H2 | 19044.6812 | General availability |
| 22H2 | 19045.6812 | General availability |
Security
No vulnerabilities are listed for this update.
Downloads (Microsoft Update Catalog)
Updated components
38 files changed since the previous update for the same versions.
Sources
Cited passages from Microsoft's official notes (3)
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1.
Fixed: After installing the Windows update released on and after January 13, 2026, some applications became unresponsive or encountered unexpected errors when opening files from or saving files to cloud-based storage, such as OneDrive or Dropbox.
support.microsoft.com -
2.
This servicing stack update (SSU) includes enhanced logic to verify whether a device is hosted on Azure, leveraging an updated certificate chain for validation.
support.microsoft.com -
3.
This issue is addressed in KB5075912.
support.microsoft.com
Checked automatically: 8 of 8 checks passed, 3 quoted passages · compared with Microsoft's page on Sep 25, 2026
- Quotes found in the official pages: passed
- Numbers found in the sources: passed
- Vulnerabilities from the dossier only: passed
- Links to allowed domains only: passed
- Every official change covered: passed
- Readable plain text: passed
- Changes confirmed by the file list: passed
- Sources agree: passed
A second AI read the text against the sources: correctness 5/5, clarity 4/5, completeness 4/5. How we work
Published by The Update Bureau. Written with AI from Microsoft's own documents, checked by rules and a second AI. How we work · Report a mistake