Fix Reboot and Select Proper Boot Device Windows 10

If you see “Reboot and Select Proper Boot Device” on a black screen in Windows 10, it means your computer cannot find a bootable operating system. The fix usually involves checking the boot order in BIOS/UEFI, reseating the hard drive, or repairing the Master Boot Record. Below is a step-by-step guide to diagnose and resolve the issue.

What Causes This Error?

This error appears during the Power-On Self-Test (POST) when the BIOS or UEFI firmware cannot locate a valid boot device. Common causes include:

• Incorrect boot order: The system is trying to boot from a USB, CD, or another drive that has no OS.
• Loose or disconnected drive cables: SATA or power cables may have come loose, especially after moving the PC.
• Corrupted boot files: The Master Boot Record (MBR) or Boot Configuration Data (BCD) may be damaged.
• Failing hard drive: The drive may be dying or have bad sectors.
• BIOS/UEFI settings changed: A recent update or CMOS reset may have changed the boot mode (Legacy vs UEFI).

How to Fix It: Step-by-Step

1. Restart and enter BIOS/UEFI: Restart your PC and press the key shown on the screen (often Del, F2, F12, or Esc) to enter the firmware setup.
2. Check boot order: In the Boot menu, ensure your primary hard drive (e.g., “SATA: 5-WDC WD5000”) is first. If a USB or CD is listed above it, change it and save (usually F10).
3. Disconnect external devices: Remove all USB drives, SD cards, and external hard disks, then restart.
4. Reseat internal cables: If you are comfortable, open the case and unplug/replug the SATA and power cables on the hard drive and motherboard.
5. Boot into Windows Recovery Environment (WinRE): If the above fail, use a Windows 10 installation USB to boot, then select “Repair your computer” > “Troubleshoot” > “Advanced options”.

Repairing the Master Boot Record (MBR)

If the boot files are corrupted, you can rebuild them from the Command Prompt in WinRE. Steps:

1. Boot from the Windows 10 USB and go to “Repair your computer” > “Troubleshoot” > “Advanced options” > “Command Prompt”.
2. Type bootrec /fixmbr and press Enter.
3. Type bootrec /fixboot and press Enter.
4. Type bootrec /rebuildbcd and press Enter. If it prompts to add an installation, type Y.
5. Exit and restart.

If you get “Access is denied” when running bootrec /fixboot, your disk may be GPT with an EFI system partition. In that case, use the diskpart tool to assign a letter to the EFI partition and then run bcdboot C:\Windows (adjust drive letter as needed).

Checking the Hard Drive Health

A failing drive can cause this error. To check its health:

• In the Command Prompt (from WinRE), run chkdsk C: /r to scan for bad sectors and attempt repairs. This can take hours.
• Listen for unusual clicking or grinding noises from the drive—these indicate physical failure.
• If the drive is not detected at all in BIOS, try a different SATA port or cable, or test it on another computer.

If the drive is failing, back up any important data immediately (using a USB adapter or another PC) and replace the drive.

UEFI vs Legacy Boot Mode

Windows 10 can boot in either UEFI (with GPT disk) or Legacy (with MBR disk). If the boot mode is changed (e.g., from UEFI to Legacy), the system won’t find the boot loader. To fix:

• Enter BIOS and look for “Boot Mode” or “UEFI/Legacy” setting.
• If your Windows was installed in UEFI mode, set it to UEFI (and disable CSM if present).
• If installed in Legacy, set to Legacy (or CSM enabled).
• If you’re unsure, try both—but note that switching without reinstalling may not work if the disk is formatted differently.

When to Reinstall Windows

If none of the above works, and the drive is healthy, the Windows installation may be too corrupted to repair. In that case, you can:

• Back up your files (if possible) using a live Linux USB or by connecting the drive to another PC.
• Reinstall Windows 10 using a USB drive. During setup, choose “Custom” and select the drive partition (usually “Drive 0 Partition 1: Primary”).

Reinstalling will erase everything on that drive, so only do this as a last resort.

Frequently Asked Questions

Will this error damage my data?

Usually not—the error is a boot-time message, not a data corruption indicator. However, if the cause is a failing drive, data loss is possible. Back up early.

Why does it happen after a power outage?

An abrupt shutdown can corrupt boot files or reset BIOS settings. The MBR repair steps above often resolve it.

Can I fix this without a Windows USB?

Yes, if you can access the Advanced Startup Options (Shift+Restart from Windows), but if you can’t boot at all, a USB is needed. You can create one on another PC using Microsoft’s Media Creation Tool.

Is this error the same as “No bootable device”?

Yes, it’s essentially the same message from different BIOS vendors. The fixes are identical.

How do I know if my drive is dead?

If the drive doesn’t appear in BIOS at all, try a different cable/port. If it still doesn’t show, it’s likely dead. If it appears but makes noise, back up immediately.

What if I see “Invalid partition table” instead?

That’s a different error indicating the MBR is corrupted or the partition is missing. The bootrec /fixmbr and /rebuildbcd steps may help, but you may need to rebuild the partition table with diskpart.

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