How to Fix Inaccessible Boot Device on Windows

What Causes This?

The Inaccessible Boot Device error usually means Windows can’t read the drive or partition it needs to start. This often happens after a failed Windows update, corrupted system files, damaged boot records, bad storage drivers, or a BIOS/UEFI setting change such as switching between AHCI and RAID modes. In some cases, a failing SSD or hard drive can also trigger it.

Common Symptoms

• Windows shows a blue screen with Inaccessible Boot Device
• The PC restarts repeatedly and never reaches the desktop
• Startup Repair fails or loops back to recovery options
• The error appears right after a Windows update, driver change, or hardware change
• Windows only boots into Advanced Startup or Recovery Environment

How to Fix It Manually

1. Disconnect external devices and restart

   • Shut down the PC completely.
   • Unplug external drives, USB sticks, SD cards, and unnecessary peripherals.
   • Turn the PC back on and check if Windows starts normally.
   • If you recently installed new internal hardware, reseat it if possible.

2. Boot into Windows Recovery Environment

   • If Windows won’t start, interrupt boot 3 times: power on the PC, and as soon as Windows starts loading, hold the power button to force shutdown. Repeat this three times.
   • On the next boot, Windows should open Preparing Automatic Repair.
   • Go to Advanced options > Troubleshoot > Advanced options.

3. Run Startup Repair

   • In Advanced options, click Startup Repair.
   • Select your Windows account and enter your password if asked.
   • Let Windows scan and repair startup problems.
   • Restart the PC and test again.

4. Remove recent updates

   • In Advanced options, choose Uninstall Updates.
   • First select Uninstall latest quality update.
   • If the problem started after a major upgrade, choose Uninstall latest feature update instead.
   • Restart and see if the blue screen is gone.

5. Check the disk and repair system files from Command Prompt

   • In Advanced options, open Command Prompt.
   • Type these commands one at a time, pressing Enter after each:

     chkdsk c: /f /r
     sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows

   • If Windows is installed on a different drive letter in recovery mode, replace C: with the correct one.
   • Wait for both scans to finish, then restart.

6. Repair boot records

   • In Command Prompt, run:

     bootrec /fixmbr
     bootrec /fixboot
     bootrec /scanos
     bootrec /rebuildbcd

   • If bootrec /fixboot returns Access is denied, continue with the other commands and restart anyway.
   • Test booting into Windows again.

7. Check BIOS/UEFI storage mode

   • Restart the PC and enter BIOS/UEFI setup by pressing Del, F2, or the key shown on screen.
   • Find the storage or SATA settings.
   • If the mode was recently changed between AHCI, RAID, or IDE, switch it back to the previous setting.
   • Save changes and restart.
   • Be careful here: changing storage mode incorrectly can prevent Windows from booting.

8. Try Safe Mode

   • From Advanced options, go to Startup Settings > Restart.
   • Press 4 for Enable Safe Mode.
   • If Windows starts, open Device Manager by pressing Windows + X > Device Manager and check storage controllers for recent driver changes.
   • You can also uninstall recently added drivers or software that may have caused the issue.

Fix It Automatically with Kudu

After you repair the boot problem, Kudu can help clean up leftover junk, fix common system issues, and optimize Windows so the PC runs more reliably. It’s a simple way to remove clutter and reduce the chance of future errors caused by broken updates, bad temporary files, or system mess.

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