Earlier this week, Michael Fortin, Corporate Vice President, Windows published a blog post on Windows 10 monthly security and quality updates. The post describes the different types of monthly updates, from the "B" releases that take place on Patch Tuesday, to optional "C" and "D" patches that Microsoft will be coming later in the month.
Today, an article from PCWorld puts an emphasis on these optional releases, and emphasizes that these C and D updates are "beta code". In its own words from Microsoft's Michael Fortin, "the purpose of these releases is to provide visibility and enable testing of non-security updates that will be included in the next update Tuesday solution."
We cover all new Windows 1
0 based on OnMSFT, and we always mentions when they come with known issues. Even Patch Tuesday updates sometimes come with known issues, so it's not only "C" and "D" updates that can be problematic.
But what PCWorld did not talk about is that Microsoft has released preview quality updates for quite some time. In our knowledge, the company has changed its update plan that begins with Windows 10 version 1703 (aka Creators Update). This is what Microsoft's Michael Niehaud explained at the time:
Based on customer feedback, we make some updates to the updates that we do not release for Windows 10, version 1703 (also known as "Creators Update"). With these changes, we will routinely offer one (or sometimes more than one) additional update each month. These additional cumulative updates will only contain new non-security updates, so they will be considered "Updates" in WSUS and Configuration Manager.
Microsoft has offered preview of upcoming non-quality fixes since the release of Windows 10 version 1703  So yes, Microsoft has released more than one new building every month for a while now and the optional quality updates released later this month, will end in Patch Tuesday for the next month. All Windows 10 updates, including these optional updates, are cumulative, which means they include all previously released fixes.
Microsoft explained its update service for Windows 10 update in August this year, which makes it clear that the optional "C" and "D" updates are only available to searchers. In addition, the company said it could sometimes be delivered "out of-band releases "to cope with critical errors that can not wait for the next Patch Tuesday." These are reserved for situations where devices must be updated immediately to fix security issues or to resolve quality issues that affect many devices, "explained the blog post. 19659002] If the blog in August was not enough, the company also published the following 3 minutes video explaining all about Windows 10 monthly updates:
Concluding, yes, Microsoft has released optional quality updates since the release of Windows 10 version 1703 last year. These updates are a preview of future quality fixes and are available only to users who Looking for updates in Windows Update. These patches will eventually end in the following Patch Tuesday, which will be pressed to all Windows 10 users.
Additionally, the optional C and D updates sometimes come with known issues, but it is also often the case with the monthly updates in Patch Tuesday. . Earlier used Microsoft Windows Insider Release Preview Call to test all new Windows 10 builds in the production ring, but the company has made this less consistent over time. Either way, you may want to keep Windows 10 update history page in your bookmarks, but you can also trust us to tell you all the details of new Windows 10 updates.
Further Reading: Cumulative Updates, Windows 10, Windows Update