Yesterday, Microsoft released a Cumulative Update for Windows 10 Creators Update, otherwise known as version 1703, which updated it to build 15063.674 as part of its Patch Tuesday update cycle - are you following? Good.

Today when people started waking up from their machines automatically updating during the night, however, they have been faced with a BSOD (Blue Screen of Death) instead of the Windows 10 desktop, and unfortunately, no-one seems to know why the installations are failing, only that it relates to KB4041676, which is yesterday's update.

On one thread at the Microsoft Answers forum, which has yet to see an official response from Microsoft, one user reported BSODs on all of his test machines, which consist of different makes of laptops and PCs (self-built, HP, and Lenovo):

I deploy patches via SCCM on a regular basis to nearly 5500 clients worldwide. My first group of Alpha systems which contains all of my own workstations receive the first round of patches as a test. ALL of the systems running 1703 blue screen upon reboot AFTER applying this patch (KB4041676). The message that comes up is INACCESSIBLE BOOT DEVICE. After that, it reboots automatically, attempts to boot again, and then displays the "Automatic Repair" screen. None of these systems make it past this message. My ALPHA test systems range from brand new Lenovo laptops, 2 Lenovo desktops, 1 Dell desktop, 2 custom built desktops, and 10 VMs. What now Microsoft?

In another comment in the same thread, another user had a similar experience, posting:

Any computers that we had on overnight and have rebooted are no longer starting up with a blue screen and INACCESSIBLE BOOT DEVICE. We've tried all the standard stuff: Bootrec /fixmbr /fixboot /rebuildos

Renamed bcd file and tried rebuildos

tried copying SAM,SOFTWARE,DEFAULT,SYSTEM from regback

tried sfc /scannow

tried dism /image:DRIVE:\ /cleanup-image /restorehealth So far NOTHING has brought the computers back. These are varying models as well across laptops and desktops, the main contributing factors are Windows 10 1703 and the KB 4041676 update.

And the list goes on, on Reddit, some people are complaining that disk usage remains at over 100% while trying to apply the update, which can take upwards of over an hour. Others are reporting that the installation is getting stuck at various points, 22% in this instance and 23% in another case reported on Microsoft Answers.

If you haven't updated yet, now would be a good time to ensure you have a System Restore point to roll back to. Additionally, you can download the Windows Update troubleshooter via this Microsoft article by following the steps, or through this direct link, running it before updating will check if you're good to go or repair previous failures to update.

Until Microsoft responds with the reason for why the update is failing, it's anyone's guess as to what is causing it, since the reports are coming in from vastly different types of machines attempting the update and failing at one point or another.

We will update this post once we have more information.

Update: Some people are commenting that the known issue posted along with the KB update:

"Systems with support enabled for USB Type-C Connector System Software Interface (UCSI) may experience a blue screen or stop responding with a black screen when a system shutdown is initiated."

- is probably the reason, but that doesn't answer why some systems without USB Type-C are having issues, including returning an install date of "1/01/1601" for the patch (Comment #1, #2).

Update #2: This appears to actually only affect WSUS users, despite multiple reports of others having isues updating outside of the Enterprise environment. Although Microsoft itself hasn't commented yet, some MVPs, forum volunteers and gurus have chimed in and even posted workarounds and fixes for those bricked (BSOD) machines that applied a Delta patch as well as the Cumulative Update (the former of which has been expired and won't download anymore) and therein was the problem. The Delta patch shouldn't have gone out with the KB update, and this has now been rectified.

For those that still need to recover their machines that updated via WSUS and then can't boot to desktop, go here for the fix, follow instructions.

Update #3 October 13: Microsoft has now confirmed a fix for this issue, see this article.

Cheers for the News Tip Chris Peters!