Inaccessible boot device after latest insider update this morning (build 21364)

Same for me. I had just changed my thermal paste on my cpu, so when this update came, at first I thought I did something wrong with my hardware, because my bios was also reset and could not boot anymore. This is unacceptable from Microsoft. We are power users, but imagine the mess for the normal persons it is when they see this issue and don't know what to do. I only hope this has not damaged my hardware in any way.

I am tired of Microsoft updates **** up my desktops so this is what I am doing about this repeated experience. Bye Bye Windows 10, Hello mint Linux!!

Same issue here, but now mitigated.

System Specs:

MB: Gigabyte AORUS X570 Master

CPU: AMD 5950X (PBO Enabled, CO Tuned To Prime Stable)

RAM: G.Skill 4x16GB DDR4-4000 16-18-18-39 1.4V (Running @ DDR4-3733 15-15-15-36 1.35V, 1866 FCLK, 1.15 VSOC)

GPU: EVGA RTX 3090 FTW3 ULTRA

Boot Drive: WD_BLACK SN850 1TB NVMe M.2

Edition: Windows 10 Pro

Version: 20H2

OS Build: 1904.964

Feature Set: 120.2212.2020.0

Steps:

Installed AMD SCSIAdapter 9.3.0221 driver update. 

BSOD inaccessible boot device on reboot.

Auto-reboot after BSOD caused the MB to freak out, fall over several times, clear CMOS (good thing I keep my tunings written down), and auto boot into BIOS recovery mode (which I didn't even know was a thing). 

Left BIOS settings on defaults.

Used Windows install USB to apply restore point.

Attempted reinstall of driver update.

Replicated behavior. BSOD, MB failures, Auto cleared CMOS, rebooted to BIOS recovery mode.

Used Windows install USB to run startup repair.

Boot to Windows successful. AMD SCSIAdapter 9.3.0221 shows as successfully installed. 

Re-applied BIOS settings and tunings and rebooted several times without incident. 

Currently re-running Prime95 to confirm stability.

Comments:

I'm not sure what startup repair did as there are no logs of it in event viewer. However, this seemed to come scary close to actually damaging my hardware. Things have to get pretty screwy for the MB to do a CMOS clear all on its own, let alone that BIOS recovery mode.

This was gross negligence on Microsoft's part. The issues with this update were well documented in the dev version and should never have been pushed to the public.

Nothing works in the recovery mode as it cannot back out the update, cannot repair. 

One of the update is kb5003399 and I forgot the other one, will have to boot back to the command prompt.

In the command prompt, I can tell it's not showing my 1TB drive, it's in x:/ with very little space.

Also, wusa.exe doesn't exist in that command prompt. 

Can anyone help to get my system booting again?

MB: GIGABYTE X570 AORUS ELITE WIFI AM4 AMD X570

CPU: AMD RYZEN 5 3600 6-Core 3.6 GHz

GPU: Nvidia 1070<feff><feff>

Memory: 64 GB (4 x 16 GB Crucial Ballistix 32GB Kit (2 x 16GB) DDR4-3600 )

Drive: Samsung 1TB 970 EVO NVMe M.2 Internal SSD

I had the same problem. The update also made my settings in the bios default to factory settings.   Just by luck I did a 'clonezilla' back up of the entire drive a few days ago. My solution was to reboot with the 'clonezilla' usb drive in and then press 'f12' and choose it. I then restored the entire windows drive successfully. I wish I could help you more. I seem to recall a setting in windows that allows you to go back before an update but you would need to be in windows to do it, assuming that would work.

+1 - I was in the middle of reinstalling windows and was extremely confused why I had inaccessible boot device only after windows update did its thing on the fresh install.  3 Fresh installs later and finally found this thread to isolate it.

Aorus Master x570 w/5900x