Error Messages

INACCESSIBLE_BOOT_DEVICE Error: How to Fix It

Updated October 2, 2026 •7 min read

Your PC starts loading Windows, then drops to a blue screen: “Your PC ran into a problem and needs to restart,” with the stop code INACCESSIBLE_BOOT_DEVICE. After a couple of failed restarts, Windows may send you to Automatic Repair. The inaccessible boot device error (bug check 0x0000007B, often shortened to 0x7B) is scary, but it rarely means your files are gone. It means Windows started loading and then lost access to the drive it was booting from.

That distinction matters. In many cases the cause is a driver or setting, and the data is still sitting on the drive.

What the inaccessible boot device error means

Early in startup, Windows loads a storage driver so it can read the system drive. If that driver doesn’t match how the drive is connected, or the file system can’t be mounted, or the drive stops answering, Windows can’t continue and stops with INACCESSIBLE_BOOT_DEVICE.

Compare that with Reboot and Select Proper Boot Device, where the firmware can’t find a bootable drive at all. Here the firmware did find it and handed off to Windows. The failure comes later.

Common causes

A storage controller mode change. Switching the SATA mode between AHCI and RAID/Intel RST, or toggling Intel VMD (common on newer Intel laptops), changes which driver Windows needs. If Windows wasn’t set up for the new mode, it can’t see its own drive. BIOS updates and resets can change this setting without you noticing.
A bad Windows update or driver update, especially one that touches storage or chipset drivers.
Drive or encryption changes. Moving the drive to a new PC, cloning to a new SSD, or changes involving BitLocker.
A corrupted file system on the Windows partition, often after a power loss or forced shutdown.
A failing SSD or hard drive that responds intermittently or not at all.

Fixes, from safest to strongest

All of these are done from the Windows Recovery Environment (WinRE). If Windows fails to boot twice in a row, it usually opens WinRE on its own. If not, boot from a Windows installation USB and choose Repair your computer.

1. Undo any recent BIOS change

If you (or a BIOS update) changed anything recently, enter BIOS setup (usually F2, F10, Del, or Esc at power-on) and check:

SATA Operation / Storage mode: if it says RAID and you think it used to say AHCI (or the reverse), switch it back.
Intel VMD: if this option exists and was recently toggled, set it back to how it was.
While you’re there, confirm the drive is detected. If it’s not listed at all, skip to “When the drive itself is failing.”

Changing these settings doesn’t write to your drive, so you can safely switch back if a change doesn’t help.

2. Run Startup Repair

Troubleshoot → Advanced options → Startup Repair. Let it finish. It can fix some boot configuration and driver-loading problems automatically.

3. Uninstall the latest update

If the error started right after Windows Update, go to Troubleshoot → Advanced options → Uninstall Updates and try Uninstall latest quality update first, then Uninstall latest feature update if needed.

4. Try Safe Mode

Troubleshoot → Advanced options → Startup Settings → Restart, then press 4 (or F4) for Safe Mode. If Windows boots, a third-party driver or software is the likely cause. Copy your important files to an external drive right away, then roll back recently installed drivers or software.

5. Check the file system, read-only first

Open Troubleshoot → Advanced options → Command Prompt. Drive letters in WinRE don’t always match normal Windows, so find the one with your files:

dir C:\
dir D:\

Then run a read-only check on the Windows drive (use the right letter):

chkdsk C:

Without any switches, chkdsk only reports problems. It doesn’t change anything. If it finds file-system errors and you have no signs of a failing drive, you can run chkdsk C: /f to repair them. Avoid chkdsk /r on a drive you suspect is failing. It reads every sector and tries to relocate bad ones, which is hours of stress on weak hardware and can make recovery harder. For more on this trade-off, see Windows stuck repairing disk errors.

If the drive is BitLocker-encrypted, WinRE will ask for the recovery key before you can reach it from the command prompt. Here’s where to find your BitLocker recovery key.

Rescue your files before reinstalling

If nothing works, don’t “Reset this PC” with “Remove everything,” and don’t do a clean install that formats the drive while your files are still on it. Instead:

If Safe Mode works, copy your files out while you can.
Otherwise, remove the drive and connect it to another computer with a USB-to-NVMe or USB-to-SATA adapter, then copy what you need. You’ll need the BitLocker recovery key if the drive is encrypted.
If the other computer offers to format or initialize the drive, decline.

A note for laptop owners: some laptops have storage soldered to the motherboard, so it can’t be removed and connected elsewhere. On those, a failed board or drive is a lab job.

When the drive itself is failing

INACCESSIBLE_BOOT_DEVICE is sometimes the first visible sign of a dying drive. Stop and power down if:

The drive isn’t detected in BIOS, or only shows up some of the time.
A hard drive clicks or beeps.
chkdsk reports a large number of errors, or the read-only scan hangs.
The error started after a drop or spill.

Further repair attempts on failing hardware tend to make things worse, not better. SSDs often fail with no warning noise at all, so a drive that has vanished from BIOS deserves the same caution.

The bottom line

The inaccessible boot device error means Windows lost access to its own drive partway through startup. Usually the cause is a BIOS storage setting, a bad update, or file-system damage, so revert recent changes, run Startup Repair, uninstall the latest update, and use a read-only chkdsk before any repairs. Get your files off before reinstalling. A related stop code is UNMOUNTABLE_BOOT_VOLUME, and on older systems the same kind of breakdown can show up as BOOTMGR is missing.

If the drive won’t respond, our laptop data recovery service can help. ClearQuote recovers single devices for one flat $1,200 price with free prepaid shipping, and you pay nothing unless we recover your data.