INACCESSIBLE_BOOT_DEVICE in Windows when booting from USB

Question

I have installed Windows on a removable USB drive, but whenever I try to boot from it, it bluescreens with an error code of INACCESSIBLE_BOOT_DEVICE. Why does this happen, and how can I make it boot again?

Answer 1

According to this thread, the USB 3.0 drivers aren't loaded at the stage of the boot process where Windows tries to access the boot partition.

To make Windows load the USB drivers sooner:

1. Press WinR, type regedit and hit Enter
2. Enter HKLM\SYSTEM\HardwareConfig\ in the address bar at the top
3. On the left, choose the entry with the UUID of the boot partition
4. Change BootDriverFlags's value to 14 (hexadecimal)

Answer 2

USBPcap can cause this on Windows To Go as well: https://github.com/desowin/usbpcap/issues/61

(Note that removing usbpcap from UpperFilters actually disables usbpcap)