Windows 10 update servicing cadence

I’ve heard from many of you that you’d like a primer on our monthly Windows 10 quality update servicing cadence and terminology. In response, I’d like to share our guiding principles, then dive into them further to provide context for the quality updates themselves.

Guiding principles

We use the following principles for the monthly Windows servicing process:

• Be simple and predictable. IT managers should be able to plan for a simple, regular and consistent patching cadence. You shouldn’t need to stop what you’re doing to test and deploy an update. You should be able to plan a time, well in advance, to work on new updates. You also shouldn’t have to memorize multiple release schedules; the Windows release cadence should align with that of other Microsoft products.
• Be agile. In today’s security landscape, we must be able to respond to threats quickly when required. We should also provide you with updates quickly without compromising quality or compatibility.
• Be transparent. To simplify the deployment of Windows 10 in large enterprises or small businesses, you should have access to as much information as you need, and you should be able to understand and prepare for updates in advance. This includes guides for common servicing tools, simple release notes, and access to assistance or a feedback system to provide input.

Monthly quality updates

Next, I’d like to offer a quick summary of our monthly quality update types:

• At times referred to as our “B” release, Update Tuesday (most often referred to as Patch Tuesday) updates are published the second Tuesday of each month. These updates are the primary and most important of all the monthly update events and are the only regular releases that include new security fixes.
• An out-of-band release is any update that does not follow the standard release schedule. These are reserved for situations where devices must be updated immediately either to fix security vulnerabilities or to solve a quality issues impacting many devices.
• The “C” and “D” releases occur the third and fourth weeks of the month, respectively. These preview releases contain only non-security updates, and are intended to provide visibility and testing of the planned non-security fixes targeted for the next month’s Update Tuesday release. These updates are then shipped as part of the following month’s “B” or Update Tuesday release.

Now let’s align our principles to our monthly quality update releases.

Be simple and predictable

Across Microsoft, we have aligned on releasing updates on the second Tuesday of every month. It is the common, shared release date for Windows updates and for other products like Office. This consistent approach gives you the ability to simplify planning, testing, and deploying in advance.

For Windows, Update Tuesday is the most important monthly service event. This quality update does not include new features; instead, it serves to enhance system stability and security. We develop and test these updates quickly to minimize the impact of a vulnerability should one be made public, and they should be installed as soon as possible once released.  

As an IT professional, you should have an established process and plan to ingest Update Tuesday releases each month.

Be agile 

As much as we try to simplify and standardize our release cadence, there will always be situations that require agility, and an out-of-band update is necessary. As mentioned earlier, out-of-band updates are reserved for security vulnerabilities in active exploit or significant quality issues that must be fixed before the next B, C or D release.

Out-of-band updates may similarly require an out-of-band effort from IT pros to test and deploy them. While you should keep an eye out for out-of-band updates, they are rare and we have set a high threshold for releasing them.

Be transparent

Due to the sensitive nature of security fixes, Update Tuesday releases must be coordinated internally between our product teams and tested externally with our partners. Non-security releases do not have this limitation so, for the latest version of Windows 10, we typically release the majority of non-security updates the fourth week of every month, two weeks after the last Update Tuesday and two weeks before the next, in a “D” release.

During the two-week period between the initial release of a D release and our active push to install them on devices, you can test the updates included in the release and provide feedback, reducing the amount of testing necessary following Update Tuesday and, thereby, improving our ability to solve issues before they even happen. 

For older versions of Windows 10 (as well as supported versions of Windows 7 and Windows 8.1), we sometimes release updates during the third week with a “C” release to provide you with extra time to test your legacy systems. In addition, as a new feature release draws near, we shift the current release to the “C” week, since there are fewer fixes and improvements necessary on the current version. Having just a few updates to test on the “C” week and none on the “D” week gives you the chance to concentrate on other responsibilities and frees up time for when the next semi-annual update arrives.

In most cases, “C” and “D” releases do not need be deployed to your broader device ecosystem. Instead, you can use these releases to identify any issues that could impact your next “B” deployment and provide feedback. This helps you get a head start on testing and understanding the potential impact of updates and gives you a chance to provide suggestions before those updates are officially released, providing a smoother and more tailored experience when the “B” release comes around.

The history of Update (aka Patch) Tuesday

Before I conclude this post, I wanted to provide a brief look back at the origins of our second Tuesday release schedule. “Patch Tuesday” was formalized in October 2003 after years of updates shipping whenever they were ready, a method called “ship-when-ready.” While this allowed fixes to go out almost immediately, it was a burden on IT pros, who were forced to start their workdays not knowing whether they would have to test and deploy an update. It was also a challenge for users, who sometimes had to reboot their computers multiple times a month to apply new updates, rather than just one reboot to apply a cumulative update, the process we use today.

We chose the second Tuesday at 10:00 a.m. Pacific time for two reasons:

• To provide you with a day (Monday) to deal with any other issues you need to work through from the previous week.
• To give you plenty of time to test the updates and deploy them to devices, then respond to any issues that may arise during the rest of the week.

Microsoft also spends the rest of the week watching for feedback and issues identified by businesses and consumers so we can begin preparing fixes immediately if necessary. 

In addition to giving us time to respond to user feedback, the Update Tuesday schedule has enabled us to employ artificial intelligence in our deployment process. As John Cable noted back in June, “We continuously collect update experience data and retrain our models to learn which devices will have a positive update experience, and where we may need to wait until we have higher confidence in a great experience. Our overall rollout objective is for a safe and reliable update, which means we only go as fast as is safe.” This careful, strategic approach ensures that devices will be updated quickly and without any problems, even if we don’t have those specific devices available to test on, so that users can enjoy a seamless update experience. 

Learn more

I hope this provides helpful insight into the rhythm of Windows quality updates and how they align to our servicing principles. For an overview of our monthly update process in just three minutes, check out this video:

If you’re interested in learning more about release channels, or would like to see how you can use tools like System Center Configuration Manager , Windows Server Update Services (WSUS), or Windows Update for Business to manage updates, see the Quick guide to Windows as a service. To learn more about Windows as a service, check out the Windows as a service page on the Windows IT Pro Center.