The Problem
At power-on you get No bootable device, Operating System not found, Reboot and select proper boot device, or No boot device available. Firmware looked for something to boot and found nothing it recognised.
Causes run from trivial to terminal: a USB stick ahead of the SSD in the boot order, a firmware setting that was reset, a damaged bootloader, a loose cable, or a dead drive.
If Windows starts and then loops, that is different: Automatic Repair loop or stuck on the loading screen.
Step 1: The Two Free Checks
Unplug every USB device except keyboard and mouse—external drives, sticks, phones, card readers—and restart. A bootable USB stick left plugged in produces this error constantly.
Reseat the drive if the PC was recently opened, moved, or transported. Power off, unplug from the wall, and reseat the SATA data and power cables or the M.2 module. A partially seated M.2 stick gives exactly this symptom.
Step 2: Does Firmware See the Drive?
This is the question that decides everything else.
- Power on and tap Del, F2, F10, or Esc to enter BIOS/UEFI. See how to enter BIOS or UEFI settings.
- Open the main information page or the storage configuration page.
- Look for your SSD or hard drive by model name.
Drive not listed → hardware. Reseat it again, try a different SATA port and cable, or move the M.2 to another slot. If it is still invisible, test the drive in another machine. A drive that no firmware detects has usually failed.
Drive listed → the hardware is alive and the problem is the boot configuration. Continue.
Step 3: Fix the Boot Order
- In firmware, open the Boot menu.
- You are looking for Windows Boot Manager, not just the drive name. On a UEFI system, that entry is what actually boots Windows.
- Move it to first position.
- Save and exit (usually F10).
If Windows Boot Manager does not exist as an option, the EFI boot entry has been lost—Step 5 rebuilds it.
Step 4: Check the Boot Mode and Secure Boot
A mismatch here breaks boot on an otherwise healthy system, and it is the usual cause after a CMOS reset or a firmware update.
- Boot Mode must be UEFI for a modern Windows 11 install. If CSM or Legacy has been enabled, turn it off.
- Secure Boot should be on for Windows 11, but if the install predates it being enabled, a mismatch can stop boot—try both once.
- Also check SATA Mode is AHCI rather than RAID, unless you deliberately use RAID. A change here also causes INACCESSIBLE_BOOT_DEVICE.
Step 5: Rebuild the Bootloader
Boot from a Windows 11 installation USB → Repair your computer → Troubleshoot → Command Prompt.
Find the right drive letter first—in recovery, Windows is often not on C:
diskpart
list volume
Note the large NTFS volume's letter and the small FAT32 EFI partition, then exit.
Repair attempts, in order:
bootrec /fixmbr
bootrec /fixboot
bootrec /scanos
bootrec /rebuildbcd
If bootrec /fixboot returns Access is denied on a UEFI system—which is normal—rebuild the EFI boot files instead:
bcdboot C:\Windows /s S: /f UEFI
where S: is the EFI system partition. If it has no letter, assign one in diskpart with select volume <n> then assign letter=S.
Step 6: Run Startup Repair
From the same recovery menu, Startup Repair. Let it complete. Run it once—if it fails twice it will not succeed on a third attempt.
Step 7: Check the Disk for Damage
chkdsk C: /f /r
Bad sectors reported here mean the drive is failing, and any fix is temporary. Get your data off it first.
What Not to Do
- Don't initialize the disk if another PC offers to. That rewrites the partition table and destroys your data.
- Don't clean-install before recovering files. The partition is normally readable from another machine or a live USB.
- Don't run
diskpart clean. It wipes the partition table entirely—people reach for it after reading forum posts about a different problem.
Still No Boot Device?
- Firmware never sees the drive → assume it has failed or is disconnected: check SSD or hard drive health on another machine.
- No display at all, no logo, no beeps → this is not a boot error: PC won't turn on.
Drive detected but unbootable? Recover important files first with RecoverPro before reinstalling Windows.
Seeing "Boot Device Not Found — Hard Disk (3F0)"? That is HP's wording for the same condition, and their firmware diagnostics give a faster answer: fix Boot Device Not Found (3F0). Had a dual-boot menu that stopped appearing? See fix a missing dual-boot menu.
Related guides
How to Detect and Remove a Rootkit in Windows 11
Malware that survives every scan and reinstall is hiding below Windows. Detect a rootkit or bootkit, remove it properly, and know when a clean install is the only answer.
How to Fix a Missing Dual-Boot Menu in Windows 11
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How to Fix Boot Device Not Found (3F0) on Windows 11
Error 3F0 appears before Windows even starts — the firmware cannot see a bootable drive. Work through boot order, detection, and BCD repair in that order.
How to Fix PFN_LIST_CORRUPT in Windows 11
PFN_LIST_CORRUPT means Windows' index of physical memory pages was damaged. Test the RAM first, then the storage driver — here is the order that works.
How to Fix BAD_SYSTEM_CONFIG_INFO in Windows 11
BAD_SYSTEM_CONFIG_INFO means the registry or boot configuration is damaged. Repair BCD, restore the registry hives, and get back into Windows 11 with these ordered steps.