BSOD 123 (INACCESSIBLE_BOOT_DEVICE): causes and diagnosis

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: INACCESSIBLE_BOOT_DEVICE windows lost access to the system partition during startup. Parameter 1 points to either a Unicode device path or the device.

Could be also:
Constant	Type	OS
ERROR_INVALID_NAME	Win32 error	Windows
EPFNOSUPPORT	errno	Solaris
ENOPROTOOPT	errno	Windows

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KERNEL_DATA_INPAGE_ERROR	BUGCODE_NDIS_DRIVER

INACCESSIBLE_BOOT_DEVICE

INACCESSIBLE_BOOT_DEVICE meaning

INACCESSIBLE_BOOT_DEVICE is bug check 0x0000007B. Windows lost access to the system partition during startup. Parameter 1 points to either a Unicode device path or the device object that could not be mounted; Parameters 2 through 4 are normally zero.

How to analyze INACCESSIBLE_BOOT_DEVICE

Determine whether the boot device is visible to firmware and Windows recovery, then check controller mode, storage driver availability, boot-critical registry configuration, disk path, encryption state, file-system health, and recent hardware or imaging changes.

Preserve the complete dump, all four parameters, Windows build, loaded modules, and the event timeline before changing drivers or firmware while investigating INACCESSIBLE_BOOT_DEVICE.
Run !analyze -v and follow the parameter-specific objects and the stack associated with INACCESSIBLE_BOOT_DEVICE rather than relying only on the symbolic name or a single probable-cause line.
Compare multiple dumps when available; a stable instruction or object path associated with INACCESSIBLE_BOOT_DEVICE is stronger evidence than a module that appears only after earlier corruption.

Recovery boundary for INACCESSIBLE_BOOT_DEVICE

Restore the expected storage path or boot-critical driver before changing partitions. Avoid initializing, cleaning, or reformatting the disk while the boot volume and data are still being diagnosed.

Official references for INACCESSIBLE_BOOT_DEVICE

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