Fix INACCESSIBLE_BOOT_DEVICE Error and Start Windows

`INACCESSIBLE_BOOT_DEVICE` means Windows cannot read the disk or partition it needs to start. The usual fixes are to restore a changed BIOS/UEFI or storage-driver setting, undo a recent update or driver, repair Windows files, or address a connection or failing drive. Start with WinRE and hardware checks, and protect your personal files before running disk repairs or reinstalling Windows.

What changed just before Windows stopped booting?

The timing can identify the right repair. If the error appeared immediately after a Windows update, storage-controller driver update, or firmware update, suspect a software change first. If it began after changing BIOS/UEFI settings, replacing or cloning a drive, or adding storage hardware, check the boot configuration and physical connections first.

You may see this exact message on a blue recovery screen:

INACCESSIBLE_BOOT_DEVICE

Make a short list of what happened before the first failed boot:

• A Windows update or feature upgrade completed, or Windows restarted during one.
• A storage, chipset, Intel Rapid Storage Technology, AMD RAID, or motherboard driver changed.
• BIOS/UEFI was reset, updated, or switched between storage modes such as AHCI, RAID, or IDE.
• Windows was cloned to a different SSD or hard drive.
• An SSD, hard drive, controller card, or motherboard was installed or removed.
• The computer became unusually slow, made unusual noises, froze, or showed disk-related warnings.

A cloned drive can fail to boot if the clone is incomplete, the wrong disk is first in the boot order, the partition layout differs, or Windows was configured for a different storage mode. A drive that was disappearing before the error, or is missing from BIOS/UEFI, is more likely to have a connection, power, controller, or hardware problem than a simple damaged boot record.

If the drive may be failing or contains files you cannot replace, avoid repeated forced restarts. Use the recovery environment to copy files first when possible.

Can your PC still see the Windows drive?

Before running repair commands, determine whether the firmware and Windows Recovery Environment can see the system disk. These checks apply to supported Windows 10 and Windows 11 installations, including PCs using UEFI, and to older Windows systems with similar recovery options. Most recovery repairs require an Administrator account. Some menus require a restart, and changing boot or storage settings can affect startup, so record the original values before changing them.

Enter Windows Recovery Environment (WinRE) by turning the PC on and interrupting startup two or three times, or boot from a Windows installation or recovery USB and choose Repair your computer. If Windows displays an automatic-repair screen, choose Advanced options.

1. Open the recovery menu.

Troubleshoot > Advanced options

2. Restart into firmware settings from WinRE if that option is available, or use the manufacturer’s firmware key during startup. Common keys include F2, Delete, Esc, and F12, but the correct key depends on the PC.
3. In BIOS/UEFI, check whether the SSD or hard drive appears in the storage or device list. If it does not, shut the PC down, disconnect power, and check the drive’s power and data connections. For an M.2 drive, reseating it may help, but only if you can do so safely and without invalidating a warranty.
4. Check the boot mode and storage-controller mode. A Windows installation made for UEFI normally needs UEFI boot, while an older installation may use Legacy or Compatibility Support Module mode. Do not switch AHCI, RAID, or IDE casually; changing that mode can itself cause this error. If a BIOS reset caused the problem, restore the previous mode rather than guessing.
5. Check the boot order. Put the Windows Boot Manager associated with the correct drive ahead of other disks or USB devices.

If the drive is visible in BIOS/UEFI but not in WinRE, the recovery USB may lack the storage-controller driver or the partition may be damaged. If it is visible in neither place, stop before running disk repairs and investigate the connection, adapter, controller, or drive health.

BitLocker may require a recovery key before WinRE can access the Windows volume. Use the key associated with the Microsoft account, work or school account, printed record, or saved file used when BitLocker was enabled. Do not guess or repeatedly alter firmware settings while a BitLocker prompt is present; save the recovery key and identify the correct encrypted volume first.

Try these fixes from safest to most advanced

Work through these in order. The first options are reversible and normally preserve personal files. Run recovery commands from WinRE’s Advanced options > Command Prompt; drive letters in WinRE may differ from those used in normal Windows. In the examples below, replace C: only after checking which volume contains the Windows folder.

Startup Repair

1. From WinRE, run the automatic repair tool.

Troubleshoot > Advanced options > Startup Repair

Startup Repair checks common boot files and startup configuration problems. If it reports that it could not repair the PC, that does not prove the drive is bad; continue with the next option.

Safe Mode and a recent driver

1. From WinRE, choose the startup settings menu.

Troubleshoot > Advanced options > Startup Settings > Restart

2. Press 4 or F4 for Safe Mode, or 5 or F5 for Safe Mode with Networking.

If Safe Mode starts, open Device Manager and inspect storage controllers, disk drives, and chipset devices. Roll back a storage or chipset driver installed immediately before the failure, then restart normally. A normal boot indicates that the previous driver was likely involved. If Safe Mode fails with the same error, do not keep forcing it; try update removal or System Restore.

Remove a recent update

1. From WinRE, open the update-removal menu.

Troubleshoot > Advanced options > Uninstall Updates

2. Try Uninstall latest quality update first. If the problem began after a major feature upgrade, the feature-update option may be appropriate.

Removing an update may restore the previous storage driver or boot configuration. If Windows cannot remove it or the error remains, continue without deleting personal files.

Use System Restore

1. Open System Restore from WinRE.

Troubleshoot > Advanced options > System Restore

2. Select a restore point dated before the failure and confirm the affected Windows installation.

System Restore normally leaves personal files alone but can remove drivers, updates, and applications installed after the selected point. If there are no restore points or the restore fails, move on.

Check the disk and Windows files

First identify the Windows volume. In Command Prompt, run diskpart, then list volume; look for the volume containing the Windows directory. Type exit to leave DiskPart. Do not select or clean a disk unless you are certain it is the correct one.

chkdsk can repair file-system structures and may make damaged files harder to recover. If the drive is failing, unusually slow, disappearing, or contains irreplaceable data, copy or recover files before running it.

1. Check the file system on the confirmed Windows volume. Replace C: with the correct letter.

chkdsk C: /f

The expected result is a completion message reporting that Windows made repairs or found no problems. /r also searches for bad sectors and can take much longer while putting extra stress on a failing drive, so use it only when the drive appears stable and you have protected your files.

2. Check protected Windows files while offline. The drive letter shown here must contain the Windows directory.

sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows

SFC should report that it repaired files, found no integrity violations, or could not repair some files. If it cannot run because the paths are wrong, identify the volume again rather than applying the command to another disk.

3. If SFC cannot repair the installation, service the offline Windows image. The component-store source may differ by release, so this command can fail if the image is badly damaged or the required source is unavailable.

DISM /Image:C:\ /Cleanup-Image /RestoreHealth

Run SFC again after DISM completes. If DISM says the image cannot be found, confirm the Windows volume letter and installation rather than changing random paths.

Repair boot configuration only when it matches the symptom

Boot-record repairs are not a general solution for every INACCESSIBLE_BOOT_DEVICE case. They are more useful when the Windows partition is present, firmware detects the drive, and the error followed a clone, partition change, or boot-configuration problem.

Do not use diskpart clean, format commands, or commands that rebuild partitions as a first repair. They can destroy access to personal files. Do not copy boot files to a guessed drive letter.

1. Find the EFI System Partition and the Windows volume in DiskPart. The EFI partition is usually a small FAT32 partition; do not select the Windows volume by size alone.

diskpart
list volume
exit

2. If the PC uses UEFI, assign a temporary letter to the confirmed EFI partition, then recreate the boot files from the confirmed Windows directory. In this example, S: is the EFI partition and C: is Windows.

bcdboot C:\Windows /s S: /f UEFI

A successful message indicates that boot files were created. If the command reports failure, recheck the partition letters, BitLocker state, firmware mode, and disk health. Legacy BIOS systems use a different boot arrangement, so do not apply the UEFI command blindly.

If the drive is not detected, repairs to SFC, DISM, or the boot configuration cannot make failing hardware appear. Return to the cable, power, controller, firmware-mode, and drive-health checks instead.

How do you know the repair worked?

Restart from WinRE and remove any USB installer or recovery drive so the PC boots from the internal Windows disk.

1. Choose Continue or restart normally.
2. Confirm that Windows reaches the sign-in screen without returning to WinRE or showing the blue-screen error.
3. Sign in and restart again. A single successful boot is not enough if the problem followed an update or drive change; confirm that Windows starts consistently.
4. Open Disk Management and verify that the expected system disk and partitions are present. Check Device Manager for warning icons under storage controllers and disk drives.
5. Check Event Viewer for recurring storage errors.

Event Viewer > Windows Logs > System

Look for repeated disk, storahci, stornvme, RAID, controller, or file-system errors around the time of the failed starts. A few old errors do not automatically identify the cause, but repeated new errors are a reason to back up and test the drive.

If Windows still boots only intermittently, freezes, loses the drive, or returns to INACCESSIBLE_BOOT_DEVICE, treat the repair as incomplete. Test the SSD or hard drive with the manufacturer’s diagnostic utility or a reputable health tool, and check SMART status where the hardware exposes it. A healthy boot after a boot-record repair does not prove the drive itself is healthy.

Prevent the error from becoming a data-loss problem

Back up personal files before deeper repairs, especially before using chkdsk /r, cloning again, replacing partitions, or reinstalling Windows. If Windows will not start, use WinRE Command Prompt, a bootable recovery environment, or another computer to copy files to a separate disk. Make sure the copied files actually open; an unchecked backup may not be usable.

Keep the BitLocker recovery key somewhere you can reach without the affected PC. A BIOS reset, motherboard change, or altered boot configuration can trigger recovery even when the files are intact.

Create Windows recovery media while the computer still works, and record the original BIOS/UEFI storage mode and boot mode before firmware changes. Keep firmware and storage drivers matched to your PC or motherboard, and avoid switching AHCI, RAID, and Legacy/UEFI settings as an experiment.

Stop troubleshooting and seek professional data recovery or repair when:

• The drive is absent from BIOS/UEFI or repeatedly disconnects.
• The computer makes unusual mechanical noises, becomes extremely slow, or reports worsening SMART health.
• Files are irreplaceable and you have not made a verified copy.
• chkdsk reports extensive bad sectors or the system crashes during disk access.
• The error returns after a clean, correctly configured boot and the drive’s health is questionable.

Replacing a failing drive is safer than repeatedly forcing repairs on it. After your files are secure, install Windows on a known-good drive or have a qualified technician handle the clone or recovery.

Conclusion

First confirm that BIOS/UEFI detects the correct drive and that its boot and storage modes match the original setup. Then use WinRE’s reversible tools before targeted file-system or boot repairs. If the disk disappears, shows health warnings, or contains files you cannot replace, stop repairing and protect the data.

Frequently Asked Questions

Will fixing `INACCESSIBLE_BOOT_DEVICE` delete my files?

Startup Repair, Safe Mode, update removal, and System Restore are normally designed to preserve personal files. Disk repairs can change file-system structures, and commands such as `clean` or formatting can destroy access to data. Back up or recover important files before advanced repairs.

Why does the error appear after changing AHCI or RAID in BIOS?

Windows loads a storage driver that matches the controller mode used during installation. Switching between AHCI, RAID, IDE, or related modes can leave Windows unable to communicate with the boot drive. Restore the previous setting unless you are deliberately following a documented conversion procedure.

Can I fix this error if the SSD is missing from BIOS/UEFI?

Software commands usually cannot repair a drive that firmware cannot detect. Check power, cables, the M.2 seating, controller settings, and another compatible slot or adapter if available. If the drive remains absent or contains important data, stop and seek hardware or data-recovery help.

Do I need to reinstall Windows?

Not usually as the first step. Reinstallation may fix severe system corruption, but it can erase applications and personal files and will not repair a failing or undetected drive. Consider it only after backups, hardware checks, and the safer recovery options have failed.