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Difficulty: HardTroubleshooting Windows OS Startup and Boot Errors

A technician is troubleshooting a Windows 11 workstation that displays a Stop Code screen with INACCESSIBLE_BOOT_DEVICE during startup immediately after a motherboard firmware update reset the UEFI/BIOS setup to factory defaults. The technician verifies that the NVMe solid-state drive is physically detected in the UEFI setup utility. Which of the following actions should the technician take first to resolve this boot error?

  1. Reconfigure the storage controller mode (AHCI vs. RAID/NVMe) in the UEFI settings to match the original OS configuration.Answer
  2. B
    Boot into the Windows Recovery Environment (WinRE) command prompt and execute bootrec /fixmbr to rebuild the Master Boot Record.
  3. C
    Boot into WinRE and execute sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows to repair system file corruption.
  4. D
    Access Task Scheduler within Computer Management via WinRE to re-enable startup hardware services.

Answer

Reconfigure the storage controller mode (AHCI vs. RAID/NVMe) in the UEFI settings to match the original OS configuration.
The correct option addresses the root cause of the error. When UEFI firmware settings are reset to defaults, storage controller modes (such as Intel VMD/RAID vs. Standard AHCI) often revert. If the Windows storage stack driver expects RAID/VMD mode but the controller is operating in AHCI mode (or vice versa), Windows cannot initialize the boot device driver and fails with the Stop Code INACCESSIBLE_BOOT_DEVICE. Reverting the controller mode in UEFI resolves the mismatch.

Step-by-Step Solution

1
Analyze the boot error symptom and recent change history.
The error INACCESSIBLE_BOOT_DEVICE occurred right after a UEFI firmware update reset settings to default values.
Firmware resets frequently revert storage controller settings (AHCI/RAID/VMD) to factory defaults, which prevents the Windows kernel boot driver from interfacing with the storage drive properly.
2
Identify the non-destructive, configuration-level resolution.
Entering UEFI settings and toggling the storage controller mode restores the hardware state expected by the installed Windows storage driver.
Matching the controller mode to the pre-reset state immediately allows Windows to locate and mount the boot partition without requiring OS repairs or partition modifications.

Key Concept

Troubleshooting Windows UEFI storage controller mode mismatches causing INACCESSIBLE_BOOT_DEVICE Stop errors.
Estimated Time:2m 0s
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Topics

Troubleshooting Windows OS Startup and Boot Errors

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