If you've spent years mastering the ins and outs of Windows Update, prepare to do some unlearning. Windows 10, with its emphasis on "Windows as a service," keeps rewriting the rules of updates and upgrades. Here's what you need to know. [Updated June 2020]
With Windows 10, Microsoft has completely rewritten the Windows Update rule book. For expert users and IT pros accustomed to having fine-grained control over the update process, these changes might seem wrenching and even draconian.
You can't pick and choose which updates to install? There's no option to delay updates on PCs running Windows 10 Home? Upgrades to new versions are mandatory?
Welcome to Windows as a service.
The new update rules are designed to solve some nagging problems in the PC ecosystem. For example, if every user can choose some updates and reject others, the number of potential configurations approaches infinity; Microsoft argues that all those untested variations make effective quality assurance much more difficult.
Likewise, Microsoft's generous 10-year support lifecycle has enabled fragmentation in the installed base: Over the past decade, Microsoft's engineering staff have been required to support as many as five major versions at the same time. In a world where security challenges arrive at breakneck speed, that fragmentation stretches support resources to the breaking point.
And thus a new approach to Windows Update, whose goals are to have the majority of Windows users fully patched at all times, with only a few versions to support and an installed base that is mostly running one of the two most recent versions. But pushback from frustrated customers resulted in major adjustments in 2018 and 2019, with a new round of changes in 2020. (For details on the most recent changes, see "Microsoft removes manual deferrals from Windows Update by IT pros 'to prevent confusion'.")
This FAQ covers the details you need to know, especially if you're the administrator in an un-managed environment.
What kind of updates are available for Windows 10?
Microsoft provides two types of update packages for Windows 10:
Feature updates are the equivalent of what used to be called version upgrades. They include new features and require a multi-gigabyte download and a full setup. Each version update gets a major version number that corresponds to its date of release, in the yymm format, as well as a build number that identifies it. Version 1909, for example, was finalized in September 2019 and is identified as build 18363. Microsoft's schedule delivers Windows 10 feature updates twice a year.
Quality updates address security and reliability issues and do not include new features. These updates are cumulative, and they increment the minor version number after the major version number. The June 2020 cumulative update for version 1909, for example, is 18363.900. Even if you skip several months' worth of updates, you can install the latest cumulative update and you will be completely up to date.
All available security and reliability updates are included in a cumulative update and cannot be selected or rejected individually. That's a major change from previous versions and a big surprise to anyone upgrading to Windows 10 for the first time.
Besides these cumulative updates, you might see servicing stack updates delivered separately. These update packages fix issues in the code that Windows 10 uses to scan for and process updates. Security updates for Adobe Flash Player and definition updates for Windows Defender are also delivered as separate packages, not included in cumulative updates.
Hardware drivers and firmware updates can be delivered through Windows Update. Typically, these packages are provided only when the driver fixes a bug that causes instability on targeted systems.
How are updates delivered in Windows 10?
For consumers and small businesses, both quality and feature updates are delivered via Windows Update. Organizations can use internal update management solutions, such as Windows Server Update Services, to distribute updates to computers on a corporate network.
Feature updates are made available to business and home editions of Windows at the same time, in what Microsoft calls the Semi-Annual Channel. (Until 2019, there were separate servicing channels, also called branches, for home and business customers. For details about this change, see "Windows 10: Has Microsoft cleaned up its update mess? (Spoiler: no)")
Because of the enormous number of machines that receive Windows updates, Microsoft "throttles" update delivery to manage the load on its servers. As a result, it may take weeks or even months for a feature update to be offered to all of the hundreds of millions of devices in each servicing channel.
Quality updates are delivered at the same time to all supported Windows 10 versions. These cumulative updates arrive on the second Tuesday of each month, or Patch Tuesday, as it's widely known. (Microsoft officials refer to this day as Update Tuesday.)
Microsoft may deliver additional updates throughout the month, including cumulative updates and servicing stack updates. So-called out-of-band patches to address critical security issues may appear at any time, generally in response to reports that a Windows flaw is being actively exploited.
Why are some cumulative updates listed as optional?
As noted earlier, Microsoft releases cumulative updates on the second Tuesday of each month. This is called the "B" release. During the third and fourth week of each month, you might see "C" and "D" releases. These cumulative updates represent previews of the following month's "B" release, and they contain only non-security fixes.
According to Microsoft, the "C" and "D" releases are "intended to provide visibility and testing" of those fixes for IT pros and enterprise administrators.
These preview releases are not installed automatically. They are visible only if you go to the Windows Update page in Settings and manually check for updates. The only way to install one of these optional updates is to click the Download And Install Now link below its entry, as shown here:
If you leave the Windows Update page without installing that update, nothing happens. The optional update disappears the following month, when it's replaced by the regular Patch Tuesday update.
Note that as a result of the global coronavirus pandemic, Microsoft briefly suspended delivery of the "C" and "D" updates in early 2020. These updates resume in July 2020.
How can I tell which updates are installed?
See the list under Settings > Update & Security > Windows Update > View Installed Update History. The list is divided into three groups: Quality Updates, Driver Updates, and Other Updates. Click the entry for any update to see further details about that update, if they're available.
How do I know whether my system is up to date?
Follow this link for instructions on how to identify the build installed on your device and compare it to the master list of Windows 10 updates:
To review an up-to-the-minute list of updates for all currently supported Windows 10 versions, see the official Windows 10 Update History page. (Use the links in the navigation pane on the left to choose a specific Windows 10 version.)
When does Windows 10 install updates?
Windows 10 downloads cumulative updates in the background and installs them automatically. As noted earlier, optional updates released in the "C" and "D" weeks are not installed automatically. In addition, as of version 1903, feature updates are also not installed automatically unless the current device is approaching its end-of-support date.
Using options on the Windows Update page in Settings, you can specify Active Hours (a block of up to 18 continuous hours) when you don't want to be interrupted by these installations. In theory, that prevents a large update from interfering with your workday activities, although the strategy fails if you shut your device down at the end of the day and don't restart until the next day.
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Windows 10 offers additional notification options as well as the option to choose a specific time (during your lunch break, for example) when updates will be installed.
Can I delay the installation of updates?
As of version 1903, Windows 10 no longer installs feature updates automatically. Instead, as with the optional cumulative updates delivered in the "C" and "D" weeks, the update is listed as available in Windows Update, but you have to click Download And Install to kick off the installation. This change affects all editions, including Windows 10 Home.
If you choose not to click that link, Windows 10 will respect your decision, but not indefinitely. For retail editions of Windows (Home and Pro), each version is supported for 18 months from its initial release date. When you approach the end of that period, Windows Update will notify you that it plan to install an upgrade to the current version; you can choose the installation time within a narrow range of dates, but you can't delay the installation indefinitely.
If you're running a version of Windows 10 Home earlier than version 1903, there is no supported way to delay the installation of cumulative updates, and when a feature update is available, it will install in the next window outside Active Hours. You can try various workarounds, such as shutting off the Windows Update service or setting your network connection as metered, but these only briefly postpone the inevitable.
As of version 1903, all publicly released (non-Insider) editions of Windows 10 allow users to pause all updates. The option to pause for 7 days is available on the main Windows Update page in all editions. In business editions (Pro, Enterprise, Education), you can use the Advanced Options button to choose a specific date up to 35 days in the future. For full details about this feature, see "Windows 10 tip: When you should (and shouldn't) pause updates."
In Pro, Enterprise, and Education editions, you can defer feature updates for up to 365 days after their initial release. In addition, you can defer quality updates, including the monthly Patch Tuesday fixes, by up to 30 days. In Windows 10 versions up to and including version 1909, these deferral periods can be set from Settings > Update & Security > Windows Update > Advanced Options. As of version 2004, those deferral options must be set using the Local Group Policy Editor.