Windows 10: A guide to the updates

On May 18, Microsoft announced the availability of Windows 10 version 21H1, known as the May 2021 Update. But the launch of a major Windows 10 update isn’t the end of a process — it’s really just the beginning. As soon as one of Microsoft’s twice-yearly feature updates is released, the company quickly gets to work on improving it by fixing bugs, releasing security patches, and occasionally adding new features.

In this story we summarize what you need to know about each update released to the public for the most recent versions of Windows 10 — versions 2004, 20H2, and 21H1. (Microsoft releases updates for those three versions together.) For each build, we’ve included the date of its initial release and a link to Microsoft’s announcement about it. The most recent updates appear first.

Note that Microsoft has not yet begun actively pushing Windows 10 21H1 to most users. You can seek out and install the release on your PC, but why rush things? In fact, we recommend keeping 21H1 off your machine for now to avoid any bugs that may crop up with the new release.

If you’re still using an earlier version of Windows 10 or of Windows, see the Microsoft support site for info about updates to Windows 10 version 1909, Windows 10 version 1903, Windows 10 version 1809, Windows 10 version 1803, Windows 10 version 1709, Windows 10 version 1703, Windows 10 version 1607, Windows 10 version 1511, the initial version of Windows 10 released in July 2015, Windows 8.1, and Windows 7.

And if you’re looking for information about Insider Program previews for upcoming feature releases of Windows 10, see “Windows 10 Insider Previews: A guide to the builds.”

Updates to Windows 10 versions 2004, 20H2, and 21H1

There have been no Windows 10 updates since the release of version 21H1 on May 18.

Windows 10 May 2021 Update (version 21H1)

Release date: May 18, 2021

Version 21H1, called the Windows 10 May 2021 Update, is the most recent update to Windows 10. This is a relatively minor update, but it does have a few new features.

Here’s a quick summary of what’s new in 21H1:

• Windows Hello multicamera support: If you have an external Windows Hello camera for your PC, you can set the external camera as your default camera. (Windows Hello is used for signing into PCs.) Why should this change matter to you? If you have an external camera, you probably bought it because it’s superior to the built-in, internal one on your computer. So with this change, you’ll be able to use the more accurate camera for logging into your PC.
• Improved Windows Defender Application Guard performance: Windows Defender Application Guard lets administrators configure applications to run in an isolated, virtualized container for improved security. With this change, documents will open more quickly. It can currently take up to a minute to open an Office document in it.
• Better Windows Management Instrumentation (WMI) Group Policy Service support: Microsoft has made it easier for administrators to change settings to support remote work.

Updates to Windows 10 versions 2004 and 20H2 prior to the 21H1 release

KB5003173 (OS Builds 19041.985 and 19042.985)

Release date: May 11, 2021

This build includes a variety of security updates for Windows App Platform and Frameworks, the Windows Kernel, Windows Media, the Microsoft Scripting Engine, and the Windows Silicon Platform. For more details, see Microsoft’s Security Update Guide. It also updates security for Bluetooth drivers and Windows OLE (compound documents).

There are several known issues in this update, including one in which system and user certificates might be lost when updating a device from Windows 10 version 1809 or later to a later version of Windows 10. Devices using Windows Update for Business or that connect directly to Windows Update are not impacted.

What IT needs to know: Because this is a security update, it should be applied relatively soon. Over the next few weeks, check for reports about problematic issues, and if all seems well, apply the update.

(Get more info about KB5003173.)

KB5001391 (OS Builds 19041.964 and 19042.964) Preview

Release date: April 28, 2021

This update gives you quick access to an integrated feed of dynamic content, such as news, weather, sports, and more, that updates throughout the day, via the Windows taskbar. You can personalize the feed to match your interests. For more details, see Microsoft’s “Personalized content at a glance: Introducing news and interests on the Windows 10 taskbar.”

There are several known issues in this update, including one in which system and user certificates might be lost when updating a device from Windows 10 version 1809 or later to a later version of Windows 10. In addition, devices with Windows installations created from custom offline media or custom ISO images might have the legacy version of Microsoft Edge removed by the update, but not automatically replaced by the new Microsoft Edge.

(Get more info about KB5001391 Preview.)

KB5001330 (OS Builds 19041.928 and 19042.928)

Release date: April 13, 2021

This update includes a wide variety of security updates, for Windows App Platform and Frameworks, Windows Apps, Windows Input and Composition, Windows Office Media, Windows Fundamentals, Windows Cryptography, the Windows AI Platform, Windows Kernel, Windows Virtualization, and Windows Media. For details, see Microsoft’s Security Update Guide website.

There are several other security issues addressed, including fixing a potential elevation of privilege vulnerability in the way Azure Active Directory web sign-in allows arbitrary browsing from the third-party endpoints used for federated authentication.

In this build, Microsoft also removed the Microsoft Edge legacy browser and replaced it with the new Chromium-based Edge.

There are several known issues in this update, including one in which system and user certificates might be lost when updating a device from Windows 10 version 1809 or later to a later version of Windows 10. Devices using Windows Update for Business or that connect directly to Windows Update are not impacted.

What IT needs to know: Because this is a security update, it should be applied relatively soon. Over the next few weeks, check for reports about problematic issues, and if all seems well, apply the update.

(Get more info about KB5001330.)

KB5000842 (OS Builds 19041.906 and 19042.906) Preview

Release date: March 29, 2021

This update fixes a variety of minor bugs, including one that made high dynamic range (HDR) screens appear much darker than expected, and another that caused video playback to be out of sync in duplicate mode with multiple monitors.

There are several known issues in this build, including one in which System and user certificates might be lost when updating a device from Windows 10 version 1809 or later to a later version of Windows 10. Devices using Windows Update for Business or that connect directly to Windows Update are not impacted.

(Get more info about KB5000842 Preview.)

KB5001649 (OS Builds 19041.870 and 19042.870)

Release date: March 18, 2021

This out-of-band update fixes a single bug in which graphical content could not be printed.

There is one known issue in this update, in which system and user certificates may be lost when updating a device from Windows 10 version 1809 or later to a later version of Windows 10.

(Get more info about KB5001649.)

KB5001567 (OS Builds 19041.868 and 19042.868)

Date: March 15, 2021

This out-of-band update fixes a single bug, which caused a blue screen when you attempted to print to certain printers using some apps.

There is one known issue in this update, in which system and user certificates may be lost when updating a device from Windows 10 version 1809 or later to a later version of Windows 10.

(Get more info about KB5001567.)

KB5000802 (OS Builds 19041.867 and 19042.867)

Release date: March 9, 2021

This update includes a wide variety of security updates for the Windows Shell, Windows Fundamentals, Windows Management, Windows Apps, Windows User Account Control (UAC), Windows Virtualization, the Windows Kernel, the Microsoft Graphics Component, Internet Explorer, Microsoft Edge Legacy, and Windows Media. For details, see the Microsoft Security Update Guide.

There are three known issues in this update, including one in which system and user certificates might be lost when updating a device from Windows 10 version 1809.

What IT needs to know: Because this is a security update, it should be applied relatively soon. Over the next few weeks, check for reports about problematic issues, and if all seems well, apply the update.

(Get more info about KB5000802.)

KB4601382 (OS Builds 19041.844 and 19042.844) Preview

Release date: February 24, 2021

This update fixes a variety of minor bugs, including one that caused video playback to flicker when rendering on certain low-latency capable monitors, and another that sometimes prevented the input of strings into the Input Method Editor (IME).

(Get more info about KB4601382.)

KB4601319 (OS Builds 19041.804 and 19042.804)

Release date: February 9, 2021

This update fixes a bug and includes a variety of security updates. The bug fixed could damage the file system of some devices and prevent them from starting up after running chkdsk /f.

Security updates are provided for Windows App Platform and Frameworks, Windows Apps, Windows Input and Composition, Windows Cloud Infrastructure, Windows Management, Windows Authentication, Windows Fundamentals, Windows Cryptography, Windows Virtualization, Windows Core Networking, and Windows Hybrid Cloud Networking. For details, see the Microsoft Security Update Guide.

There are three known issues in this update, including one in which system and user certificates might be lost when updating a device from Windows 10 version 1809.

What IT needs to know: Because this is a security update, it should be applied relatively soon. Over the next few weeks, check for reports about problematic issues, and if all seems well, apply the update.

(Get more info about KB4601319.)

KB4598242 (OS Builds 19041.746 and 19042.746)

Release date: January 12, 2021

This build fixes a variety of security vulnerabilities, including one with HTTPS-based intranet servers, and a security bypass vulnerability in the way the Printer Remote Procedure Call (RPC) binding handles authentication for the remote Winspool interface.

There are also security updates to Windows App Platform and Frameworks, Windows Media, Windows Fundamentals, Windows Kernel, Windows Cryptography, Windows Virtualization, Windows Peripherals, and Windows Hybrid Storage Services. For details see the Microsoft Security Update Guide.

There are two known issues in this update, including one in which system and user certificates might be lost when updating a device from Windows 10, version 1809.

What IT needs to know: Because this is a security update, it should be applied relatively soon. Over the next few weeks, check for reports about problematic issues, and if all seems well, apply the update.

(Get more info about KB4598242.)

KB4592438 (OS Builds 19041.685 and 19042.685)

Release date: December 8, 2020

This update fixes a security vulnerability by preventing applications that run as a SYSTEM account from printing to “FILE:” ports. It also has security updates for the legacy version of Microsoft Edge, the Microsoft Graphics Component, Windows Media, Windows Fundamentals, and Windows Virtualization. For details see the Microsoft Security Update Guide.

What IT needs to know: Because this is a security update, it should be applied relatively soon. Over the next few weeks, check for reports about problematic issues, and if all seems well, apply the update.

(Get more info about KB4592438.)

KB4586853 (OS Builds 19041.662 and 19042.662) Preview

Release date: November 30, 2020

This build fixes a wide variety of bugs, including one that caused Narrator to stop responding after you unlock a device if the app was in use before you locked the device, and another that made makes the touch keyboard unstable in the Mail app.

There are two known issues in this update, one in which system and user certificates might be lost when updating a device from Windows 10 version 1809 or later to a later version of Windows 10, and another in which users of the Microsoft Input Method Editor (IME) for Japanese or Chinese languages might experience issues when attempting various tasks.

(Get more info about KB4586853.)

KB4594440 (OS Builds 19041.631 and 19042.631)

Release date: November 19, 2020

This minor build fixes issues with Kerberos authentication related to the PerformTicketSignature registry subkey value in CVE-2020-17049, which was a part of the November 10, 2020 Windows update.

There are two known issues in this update, one in which system and user certificates might be lost when updating a device from Windows 10, version 1809 or later to a later version of Windows 10, and another in which users of the Microsoft Input Method Editor (IME) for Japanese or Chinese languages might experience issues when attempting various tasks.

(Get more info about KB4594440.)

KB4586781 (OS Builds 19041.630 and 19042.630)

Release date: November 10, 2020

This build updates the 2020 DST start date for the Fiji Islands to December 20, 2020 and includes security updates to the Microsoft Scripting Engine, Windows Input and Composition, Microsoft Graphics Component, the Windows Wallet Service, Windows Fundamentals, and the Windows Kernel. For details see the release notes for November 2020 Security Updates.

There are two known issues in this update, including one in which system and user certificates might be lost when updating a device from Windows 10 version 1809 or later to a later version of Windows 10, and another in which users of the Microsoft Input Method Editor (IME) for Japanese or Chinese languages might experience issues when attempting various tasks.

What IT needs to know: Because this is a security update, it should be applied relatively soon. Over the next few weeks, check for reports about problematic issues, and if all seems well, apply the update.

(Get more info about KB4586781.)

KB4580364 (OS Builds 19041.610 and 19042.610)

Release date: October 29, 2020

This update makes it easier to connect to others in Skype, using Meet Now from the taskbar. In addition, there are a wide variety of bug fixes, including for one that displayed the incorrect CPU frequency for certain processors, another that displayed nothing on the screen for five minutes or more during a Remote Desktop Protocol (RDP) session, and another that caused the Docker pull operation to fail due to a Code Integrity (CI) Policy that blocks the import of a Windows container image.

There are two known issues in this update, including one in which system and user certificates might be lost when updating a device from Windows 10 version 1809 or later to a later version of Windows 10, and another in which users of the Microsoft Input Method Editor (IME) for Japanese or Chinese languages might experience issues when attempting various tasks.

(Get more info about KB4580364.)

Windows 10 October 2020 Update (version 20H2)

Release date: October 20, 2020

Version 20H2, called the Windows 10 October 2020 Update, is the most recent update to Windows 10. This is a relatively minor update but does have a few new features.

Here’s a quick summary of what’s new in 20H2:

• The new Chromium-based version of the Microsoft Edge browser is now built directly into Windows 10.
• The System page of Control Panel has been removed. Those settings have been moved to the Settings app.
• The Start menu’s tiled background will match your choice of Windows themes. So the tiled background will be light if you’re using the Windows 10 light theme and dark if you’re using the Windows 10 dark theme.
• When you use Alt-Tab, Edge will now display each tab in your browser in a different Alt-Tab window. Previously, when you used Alt-Tab, Edge would get only a single window. You can change this new behavior by going to Settings > System > Multitasking.
• When you pin a site to the taskbar in Edge, you can click or mouse over its icon to see all your browser tabs that are open for that website.
• When you detach a keyboard on a 2-in-1 device, the device will automatically switch to the tablet-based interface. Previously, you were asked whether you wanted to switch. You can change that setting by going to Settings > System > Tablet.
• The Your Phone app gets a variety of new features for some Samsung devices. When using one of the devices, you can interact with the Android apps on your phone from the Your Phone app on Windows 10.

What IT needs to know: Windows 10 version 20H2 also has a variety of small changes of note for sysadmins and those in IT.

• IT professionals who administer multiple mobile devices get a new Modern Device Management (MDM) “Local Users and Groups” settings policy that mirrors options available for devices that are managed through Group Policy.
• Windows Autopilot, used to set up and configure devices in enterprises, has gained a variety of small enhancement, including better deployment of HoloLens devices, the addition of co-management policies, enhancements to Autopilot deployment reporting, and the ability to reuse Configuration Manager task sequences to configure devices.
• Microsoft Defender Application Guard now supports Office. This allows untrusted Office documents from outside an enterprise to launch in an isolated container to stop potentially malicious content from compromising computers or exploiting personal information found on them.
• Latest Cumulative Updates (LCUs) and Servicing Stack Updates (SSUs) have been combined into a single cumulative monthly update, available via Microsoft Catalog or Windows Server Update Services.
• Biometric sign-on has been made more secure. Windows Hello now has support for virtualization-based security for certain fingerprint and face sensors, which protects, isolates, and secures a user’s biometric authentication data.

For more details, see Microsoft’s “What’s new for IT pros in Windows 10, version 20H2.”

Updates to Windows 10 version 2004 prior to the 20H2 release

KB4579311 (OS Build 19041.572)

Release date: October 13, 2020

This build fixes a few minor bugs and includes a variety of security updates. Among the bugs fixed are an issue with creating null ports using the user interface, and another issue with a possible elevation of privilege in win32k.

Security updates were issued for Windows App Platform and Frameworks, Microsoft Graphics Component, Windows Media, Windows Fundamentals, Windows Authentication, Windows Virtualization, and Windows Kernel. For details, see the Release Notes for October 2020 Security Updates.

There are two known issues in this build: In one, users of Microsoft Input Method Editor (IME) for Chinese and Japanese might have issues with input. In the other, when installing a third-party driver you might receive the error “Windows can’t verify the publisher of this driver software.” You might also see the error “No signature was present in the subject” when attempting to view the signature properties using Windows Explorer.

What IT needs to know: Because this is a security update, it should be applied relatively soon. Over the next few weeks, check for reports about problematic issues, and if all seems well, apply the update.

(Get more info about KB4579311.)

KB4577063 (OS Build 19041.546) Preview

Release date: October 1, 2020

This build reduces distortions and aberrations in Windows Mixed Reality head-mounted displays and fixes a wide variety of bugs, including one that caused random line breaks when you redirect PowerShell console error output, and another that that prevented the Language Bar from appearing when a user signs in to a new session.

There is one known issue in this build: Users of Microsoft Input Method Editor (IME) for Chinese and Japanese might have issues with input.

(Get more info about KB4577063.)

KB4571756 (OS Build 19041.508)

Release date: September 8, 2020

This build includes security updates for Windows App Platform and Frameworks, Microsoft Graphics Component, Windows Input and Composition, Windows Media, Windows Shell, Windows Cloud Infrastructure, Windows Fundamentals, Windows Management, Windows Kernel, Windows Virtualization, Windows Storage and Filesystems, the Microsoft Scripting Engine, and the Microsoft JET Database Engine.

For details, see the Release Notes for September 2020 Security Updates.

The build also fixes a security vulnerability issue with user proxies and HTTP-based intranet servers, and addresses an issue with a possible elevation of privileges in windowmanagement.dll.

What IT needs to know: Because this is a security update, it should be applied relatively soon. Over the next few weeks, check for reports about problematic issues, and if all seems well, apply the update.

There is one known issue in this build: Users of Microsoft Input Method Editor (IME) for Chinese and Japanese might have issues with input.

(Get more info about KB4571756.)

KB4571744 (OS Build 19041.488)

Release date: September 3, 2020

This build fixes a laundry list of minor bugs, including one that prevented apps from downloading an update or opening in certain scenarios, another that prevented users from reducing the size of windows and another that caused File Explorer to stop working when you browsed directories of RAW images and other file types.

There is one known issue in this build: Users of Microsoft Input Method Editor (IME) for Chinese and Japanese might have issues with input.

(Get more info about KB4571744.)

KB4566782 (OS Build 19041.450)

Release date: August 11, 2020

This build includes security updates for the Microsoft Scripting Engine, Internet Explorer, Windows Graphics, Microsoft Graphics Component, Windows Kernel, Windows Input and Composition, Windows Media, Windows Shell, the Windows Wallet Service, Microsoft Edge Legacy, Windows Cloud Infrastructure, Windows Authentication, the Windows AI Platform, Windows Fundamentals, Windows Storage and Filesystems, Windows Update Stack, Windows File Server and Clustering, Windows Hybrid Storage Services, Windows App Platform and Frameworks, the Microsoft JET Database Engine, and Windows SQL components.

For details, see the Release Notes for August 2020 Security Updates.

The build also fixes an issue in Universal Windows Platform (UWP) apps that allows single sign-on authentication when an app does not have the Enterprise Authentication capability.

What IT needs to know: Because this is a security update, it should be applied relatively soon. Over the next few weeks, check for reports about problematic issues, and if all seems well, apply the update.

There is one known issue in this build: When using some apps, such as Microsoft Excel, users of the Microsoft Input Method Editor (IME) for Chinese and Japanese might receive an error, or the app might stop responding or close when attempting to drag using the mouse.

(Get more info about KB4566782.)

KB4568831 (OS Build 19041.423)

Release date: July 31, 2020

This minor build addresses a wide variety of bugs and issues, including one that caused the Settings page to close unexpectedly, which prevented default applications from being set up properly, and another that prevented some applications from printing to network printers.

There is one known issue in this build, in which when using some apps such as Excel, users of the Microsoft Input Method Editor (IME) for Chinese and Japanese might receive an error, or the app might stop responding or close when users attempt to drag using the mouse.

(Get more info about KB4568831.)

KB4565503 (OS Build 19041.388)

Release date: July 14, 2020

This build fixes several bugs, including one that might prevent you from connecting to OneDrive using the OneDrive app. It also has security updates for the Microsoft Scripting Engine, Windows App Platform and Frameworks, the Microsoft Store, Windows Graphics, Windows Input and Composition, Windows Media, Windows Shell, Windows Fundamentals, Windows Management, Windows Kernel, Windows Hybrid Cloud Networking, Windows Storage and Filesystems, Windows Update Stack, Windows MSXML, Windows File Server and Clustering, Windows Remote Desktop, Internet Explorer, Microsoft Edge Legacy, and the Microsoft JET Database Engine. For details, see the Release notes for the July 2020 Security Updates.

There is one known issue in this build, in which when using some apps, such as Microsoft Excel, users of the Microsoft Input Method Editor (IME) for Chinese and Japanese might receive an error, or the app might stop responding or close when attempting to drag using the mouse.

What IT needs to know: Because this is a security update, it should be applied relatively soon. Over the next few weeks, check for reports about problematic issues, and if all seems well, apply the update.

(Get more info about KB4565503.)

KB4567523 (OS Build 19041.331)

Release date: June 18, 2020

This minor build fixes a single issue, in which certain printers could not print, generated print errors, or caused apps and print spoolers to close unexpectedly.

There is one known issue in this build, which affects the ImeMode property to control the Input Method Editor (IME) mode for individual text entry fields to increase typing efficiency. Some IMEs in this build might have issues using the ImeMode property with certain apps, for example the input mode will not switch automatically to Kanji or Hiragana.

(Get more info about KB4567523.)

KB4557957 (OS Build 19041.329)

Release date: June 9, 2020

This build improves the reliability of voice assistants that use keywords and has security updates for the Microsoft Scripting Engine, Microsoft Edge, Internet Explorer, Windows App Platform and Frameworks, Windows Media, Windows Kernel, Microsoft Graphics Component, Windows Input and Composition, Windows Shell, Windows Silicon Platform, Microsoft Xbox, the Microsoft Store, Windows Cloud Infrastructure, Windows Fundamentals, Windows Management, Windows Authentication, Windows Cryptography, Microsoft HoloLens, Windows Virtualization, Windows Peripherals, Windows Storage and Filesystems, Windows File Server and Clustering, Windows Hybrid Storage Services, the Microsoft JET Database Engine, and the Windows Update Stack. For details, see the Release Notes for June 2020 Security Updates.

There are no known issues in this build.

What IT needs to know: Because this is a security update, it should be applied relatively soon. Over the next few weeks, check for reports about problematic issues, and if all seems well, apply the update.

(Get more info about KB4557957.)

Windows 10 May 2020 Update (version 2004)

Release date: May 27, 2020

Version 2004, called the Windows 10 May 2020 Update, is the most recent update to Windows 10. This is a relatively minor update but does have a variety of new features for both users and system administrators. For more details, see: “Review: Windows 10 May 2020 Update delivers little tweaks that add up to… well, not a lot.”

Here’s a quick summary of what’s new in 2004:

• Cortana now runs as a standalone app in a resizable window. It also loses a variety of capabilities, such as playing music, controlling home devices, and working on the lock screen.
• Task Manager now displays new information, including the temperature of your GPU and your disk type.
• Settings gets many small tweaks, including adding a header with account information, and a redone network status page that combines information that used to be found on multiple pages, such as your IP address, current connection properties and data usage.
• The Windows Subsystem for Linux (WSL) gets more features. It now uses a real Linux kernel, and is faster than previously.
• IT can now take advantage of Windows Hello biometrics logins rather than passwords, by setting that up as the default on enterprise devices.
• Installing and setting up Windows for others has been made easier thanks to new controls added to Dynamic Update, which can lead to less downtime during installation for users.
• A variety of new commands have been given to PowerShell for Delivery Optimization, a Windows networking service that reduces bandwidth consumption by sharing the work of downloading update and upgrade packages among multiple devices in business deployments.
• The security of the Chromium version of Edge has been improved, thanks to porting Application Guard to it.