Windows 10 January 2021 update has now started rolling out to
PCs running version 20H2, version 2004, and version 1909.
January Patch Tuesday release comes with important security
fixes for more than 83 vulnerabilities in the Windows operating
system and other products.
Windows 10 January 2021 update fixes a zero-day vulnerability
in the Microsoft Defender antivirus. The critical security
issue, which has now been patched, allowed attackers to run
malicious code on vulnerable devices.
The vulnerability could be exploited on unpatched systems only
when users open a malicious file and Microsoft Defender is
enabled. As part of January 2021 Patch Tuesday update,
Microsoft has also fixed bugs hitting Windows Storage Service
As always, you can apply the January 2021 cumulative updates by
following these steps:
- Open Settings and click on Update & Security.
- On the left pane, select ‘Windows Update’.
- Check for updates and click on ‘Download and install’
If you’re using Windows 10 version 20H2, you’ll get Build
19042.746 with fixes for security issues. Version 20H2 is based
on version 2004, which means Windows 10 version 2004 is also
getting the same update. For those still on version 2004,
they’ll get Build 19041.746.
Windows 10 January 2021 cumulative updates:
- KB4598243 (Build 14393.4169) for version 1607.
- KB4599208 (Build 15063.2614) for version 1703.
- KB4598245 (Build 17134.1967) for version 1803.
- KB4598230 (Build 17763.1697) for version 1809.
- KB4598229 (Build 18363.1316) for version 1909.
- KB4598242 (Build 19041.746 and Build 19042.746) for v2004
You can also download and these updates without connecting to
Windows Update. To install the Patch Tuesday update manually,
copy the KB package number from the above list and paste it in
the search box of Microsoft Update
Catalog. Once done, select the ‘Download’ button and double
click on the update package.
Windows 10 January 2021 cumulative updates overview
In addition to Defender bug, Microsoft has also fixed 83
security bugs across its Windows, developer and enterprise
tools. For example, the tech giant says it has patched an issue
that could be exploited to gain access to affected systems.
This month’s cumulative update also aims to improve the
security of the external devices that you use, such as your
keyboard, controller and even your camera.
Build 19042.746 for Windows 10 version 20H2
The January 2021 cumulative update for both Windows 10 version
20H2 and version 2004 is focused solely on security fixes. It
doesn’t come with any additional bug fixes because
Microsoft had paused the rollout of the optional updates in
As we mentioned above, Windows 10 20H2 (October 2020 Update) is
being advanced to Build 19042.746 (KB4598242)
with the following changes:
- Improvements to basic operations of the OS.
- Fixes dark mode gremlins in File Explorer.
- Fixes a security vulnerability issue with intranet
Microsoft hasn’t fixed any user-centric critical bugs, but
there are plans to deliver important fixes later this month via
optional preview update.
Windows 10 20H2 rollout status as of January 2021
Back in October, Microsoft released version 20H2 as a small
“enablement package” that can be installed in a matter of
minutes on systems running version 2004.
It has been released as an optional update and users have to
explicitly choose to download and install the updates. However,
some users have encountered compatibility issues during the
The most obvious reason, of course, is the upgrade blocks
deployed by Microsoft.
Previously, devices with outdated audio drivers would receive
Blue Screen of Death error and a warning message when users
tried to install the update.
In a new support
doc, Microsoft has confirmed that issues have now been
resolved and upgrade block is being removed. As a result, more
users can now download Windows 10 version 20H2 and the upcoming
Spring 2021 (version 21H1) update.
Later this year, Microsoft is also planning to fix a critical
bug damaging Windows 10’s Credential Manager and authentication
process. For those unfamiliar,
Windows 10 password bug is hitting a number of
applications, including Chrome, Edge, Acrobat, Lastpass, etc.
Build 18363.1316 for Windows 10 version 1909
If you’ve got a device that still uses Windows 10 version 1909,
Microsoft has published
KB4598229 with fixes highlighted above.
Starting January 2021, no new updates will be released to
devices on Windows 10 version 1903.