The update, designated as Build 9860, followed the Oct. 1 release of the preview, which Microsoft has offered businesses and technology enthusiasts to give potential customers a look at the work in progress and collect feedback during development.
The Oct. 1 version of Windows 10 was labeled Build 9841.
"Sometimes [updates] will be more frequent and sometimes there will be longer gaps, but they will always be chock full of changes and improvements, as well as some bugs and things that are not quite done," wrote Gabe Aul, of Microsoft's Operating Systems Group on a company blog today.
Aul said that Build 9860 had been handed to his group only a week ago, and repeated earlier warnings by other Microsoft managers that the preview remains incomplete and unpolished.
Although rapid iterations are nothing new to preview or beta software, Microsoft plans to accelerate the delivery of updates -- ones that will include not only security patches and performance fixes, but also new features -- once Windows 10 officially ships in mid-2015.
Updates will ship as often as monthly for consumers, while businesses will be able to choose between that and two additional tempos that Gartner has tagged as "near-consumer speed" and "long-term servicing." The former will roll up the "consumer-speed" updates every four to six months to versions that fast-acting enterprises will test and deploy, while the latter will remain feature- and UI-static for as long as two to three years, receiving only security updates.
Other analysts have contended that Microsoft is pushing frequent updates to Windows 10 Technical Preview as much to test the process -- both the back-end Windows Update service and the Windows 10 clients' ability to absorb the changes and smoothly install the updates -- as for the company's stated reasons of gathering feedback and offering users an early look.
"Changes in Windows Update were put in place to make this possible," Wes Miller, an analyst with Directions on Microsoft, said in an interview earlier this month. "The biggest question for Microsoft is how the updating process works with the Technical Preview."
In the preview, customers have an update frequently choice of only "Fast" or "Slow."
Build 9860 will be delivered automatically to most PCs running Windows 10 within days, but users can manually initiate the process by going to "PC Settings," choosing "Update and recovery" and then "Preview builds," and finally clicking the "Check Now" button.
Aul said that the download would weigh in at between 2GB and 2.7GB, and that the reboot, the reconstruction of the OS's search index, and the syncing of OneDrive would take "longer than normal" and "some time."
Microsoft will ship a second consumer-oriented preview in early 2015, but it's virtually certain that the firm will provide more-or-less-monthly updates to the Technical Preview between now and then.