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reboot and select proper boot device
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Microsoft · Windows
The BIOS/UEFI could not find a bootable operating system on any connected storage device — the system does not know where to load Windows from
Quick Answer
Error code Reboot and Select Proper Boot Device on your Microsoft Windows means: The BIOS/UEFI could not find a bootable operating system on any connected storage device — the system does not know where to load Windows from. This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
21H222H223H2Server 2019Server 2022
Likely Causes
  1. Boot order in BIOS is incorrect — a non-bootable device (USB, DVD) is set as first boot priority
  2. The SATA or NVMe cable connecting the boot drive has become loose or disconnected
  3. The boot drive has failed or is not detected by the BIOS
  4. The Windows boot partition (EFI System Partition) is corrupted
  5. BIOS boot mode mismatch — set to Legacy when Windows was installed in UEFI mode or vice versa
How to Fix It
1
Enter BIOS/UEFI (press DEL, F2, or F12 during boot) and check if your boot drive (SSD/HDD) appears in the storage/SATA device list
2
If the drive is detected, go to the Boot Priority section and move your Windows drive to the first position
3
If the drive is NOT detected: power off, open the case, and reseat the SATA data and power cables (or reseat the NVMe drive in its M.2 slot)
4
Ensure BIOS is set to the correct boot mode: if Windows was installed in UEFI mode, set boot mode to UEFI (not Legacy/CSM). Check under Boot > Boot Mode or CSM settings
5
If the drive is detected but won't boot, boot from a Windows installation USB, select 'Repair your computer' > Troubleshoot > Command Prompt, and run: bootrec /fixmbr then bootrec /fixboot then bootrec /rebuildbcd
6
For UEFI systems, instead of bootrec use: bcdboot C:\Windows /s S: /f UEFI (where S: is the EFI partition)
7
If none of the above works, the boot drive may have failed — test it in another computer or check SMART status
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Replacement SATA cable
Windows installation USB for boot repair
Replacement SSD/HDD if drive has failed
Related Error Codes
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