Windows won’t start

Blue screen 'INACCESSIBLE_BOOT_DEVICE' during startup

Windows shows a blue screen with the stop code INACCESSIBLE_BOOT_DEVICE right as it's trying to load, then usually restarts. This means Windows can't communicate with the drive that holds its own operating system.

Difficulty
Intermediate
Time
30–90 minutes
DIY cost
$0–$60
Pro cost
$100–$220

Symptoms

  • Blue screen appears very early in startup, before or right at the logo
  • Stop code reads INACCESSIBLE_BOOT_DEVICE
  • PC restarts and repeats the same error
  • Often follows a driver update, storage controller change, or drive clone

Likely causes

  • CommonStorage/AHCI driver issue after an updateA changed or corrupted storage driver can prevent Windows from talking to the boot drive.
  • CommonRecently changed BIOS storage mode (AHCI/RAID/IDE)Switching this setting after Windows is installed makes the drive unreadable to the OS.
  • PossibleCorrupted file system on the boot partitionDamage to the drive's file system can present as a total inaccessibility.
  • PossibleFailing drive with bad sectors on critical system filesPhysical degradation can make key boot files unreadable.
  • Less commonIncompatible cloned drive or connection changeMoving a drive to a different port or controller type can trigger this.

What to do

  1. Check if you recently changed a BIOS/UEFI storage controller setting; if so, switch it back to what it was and restart.
  2. Boot into Windows Recovery Environment via installation USB, choose Repair your computer, then Command Prompt.
  3. Run 'chkdsk C: /r' to scan for and attempt to repair file system and disk errors.
  4. Run 'sfc /scannow' from the same Command Prompt after chkdsk completes to repair damaged system files.
  5. Try Safe Mode by pressing F8 or using Advanced Startup > Startup Settings; if Safe Mode boots, a specific driver update is likely at fault and can be rolled back.
  6. If the drive was recently cloned or moved, verify it's connected to the same type of port/controller it was cloned for.
  7. If chkdsk reports extensive bad sectors, treat the drive as failing and back up what you can before replacing it.

Tools and parts

  • Bootable Windows installation USB drive
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When to call a pro

If chkdsk shows heavy bad-sector damage or the error returns immediately after every fix attempt, have a professional evaluate the drive for failure and recover data before replacing it.

Safety

Generally low risk

Generally low risk for a careful person. Stop if anything looks different from what this guide describes.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.