Home » Technology » Microsoft » Windows » All about the Microsoft January Patch Day for Windows 10

All about the Microsoft January Patch Day for Windows 10


Microsoft opened January Patch Day and released new updates for all Windows versions. In addition to patches for the current Windows 10 versions, there are updates for their predecessors. Everything about the patch for Windows 11 can be found in a separate article. The updates are recommended to all users as they close security gaps and introduce improvements.

All changes and available variants for desktop, server, or HoloLens are made by Microsoft in the Windows 10 update history and has published the corresponding knowledge base articles. We have compiled the available updates, detailed information on the updates is not yet available, we will submit them as soon as they are available. New updates are available for the following Windows versions:

Quick navigation

Security-related changes

Microsoft has been combining the latest servicing stack update (SSU) for the operating system with the latest cumulative update (LCU) since May. The prerequisite for this – i.e. that no individual SSU has to be installed in advance – is the patch day update from May 11, 2021, with which the change was introduced. If you use an older LCU update, you must first carry out the separately offered SSU updates (the most recent are from August 2021).

A little tip: At the start of the release it may be that the KB articles are not yet directly accessible from Microsoft. But that usually changes very quickly. About the Search the Microsoft Update Catalog but you can already find all new versions. The following list helps to check whether you have installed the latest version. There you will find the latest build numbers for the individual Windows versions. Check your installed version number with the keyboard command Windows + R to open the run dialog, the input “WinVer” then calls up the version display.

Windows 10 versions:

  • Windows 10 Version 21H2, KB5009543 (Build 19044.1466)
  • Windows 10 Version 21H1, KB5009543 (Build 19043.1466)
  • Windows 10 Version 20H2, KB5009543 (Build 19042.1466)
  • Windows 10 Version 2004, KB5009543 (Build 19041.1466)
  • Windows 10 Version 1909, KB5009545 (Build 18363.2037)
  • Windows 10 Version 1809, KB5009557 (Build 17763.2452)
  • Windows 10 Version 1607, KB5009546 (Build 14393.4886)
  • Windows 10 Version 1507, KB5009585 (Build 10240.19177)

Security updates Windows 10 Version 21H2, 21H1, 20H2, 2004

The latest Windows 10 November 2021 update (21H2) has received a new security patch. The new build number is 19044.1466. Users who have installed the May 2021 update, the October 2020 update or the May 2020 update will receive the build numbers 19043.1466, 19042.1466, and 19041.1466.


  • General security update for Windows operating system.
  • Updates a known issue affecting Japanese Input Method Editors (IME). Text entered may appear jumbled or the text cursor may move unexpectedly in applications that use the multibyte character set (MBCS).
  • Summary of Changes in Knowledge Base Article: KB5009543

Security updates for Windows 10 (from 2019)

The Windows 10 version from autumn 2019 has received an update: The new build number is 18363.2037 (for version 1909 alias November 2019 update).


  • General security update for Windows operating system.
  • Addresses an issue that causes Windows to go into BitLocker recovery after a maintenance update.
  • Enables credentials for Azure Active Directory (Azure AD) Active Directory Federation Services (ADFS) users in Quick Assist.
  • Addresses an issue that sometimes prevents Quick Assist users from using full screen view after starting a remote maintenance session.
  • Summary of Changes in Knowledge Base Article: KB5009545

Security updates for Windows 10 version 1809, 1607, 1507

The older Windows 10 versions from 2015, 2016, and 2018 have also received security updates. The security updates contain quality improvements. Overview of changes in the knowledge base articles:


Mark Goodman

Digital marketing enthusiast and industry professional in Digital technologies, Technology News, Mobile phones, software, gadgets with vast experience in the tech industry, I have a keen interest in technology, News breaking.