Fix INACCESSIBLE_BOOT_DEVICE Error on Windows 11

TL;DR: INACCESSIBLE_BOOT_DEVICE (stop code 0x0000007B) on Windows 11 means the kernel loaded but can’t talk to the drive it needs to finish booting. The most common fix is reverting a BIOS storage-mode change or running Startup Repair from a Windows 11 USB. If that fails, rebuild the Boot Configuration Database using bcdboot — not bootrec /fixboot, which always returns “Access is denied” on UEFI systems and is the wrong tool for the job.

What Causes Inaccessible Boot Device on Windows 11

Stop code 0x0000007B fires when Windows loads far enough to read your hardware but can’t reach the partition it needs to proceed. The firmware sees the drive fine. The problem is one level up: either the storage driver doesn’t match the controller the drive is connected through, the Boot Configuration Database (BCD) is pointing at the wrong partition, or the boot filesystem has enough damage that Windows can’t mount it.

Three things cause the vast majority of cases:

The BIOS SATA or NVMe mode changed after a firmware update or accidental toggle, so Windows loads a storage driver that doesn’t match the controller
A Windows Update pushed a new version of storahci.sys or stornvme.sys that doesn’t play well with your specific controller, or changed the driver’s startup type as a side effect
The BCD got corrupted, so the bootloader can’t locate where Windows lives on disk

Actual hardware failure is possible but much less common. If your SSD or NVMe drive is dying, chkdsk will surface it.

Check What Changed Right Before the BSOD

Don’t skip this. The fix almost always follows directly from the trigger.

Windows installed updates and rebooted? Most likely a broken storage driver or a corrupted BCD entry.
You updated the BIOS or poked around in BIOS settings? Check whether the SATA or NVMe mode changed.
You added or removed a drive? The boot order or BCD partition identifiers may have shifted.
You cloned Windows to a new SSD? The BCD likely still points at the old drive’s partition ID.
You didn’t do anything and it just happened? A background Windows Update is the most probable cause. Start with Fix 4 below.

Fix 1 — Revert the BIOS Storage Mode

This is the single most overlooked cause of this error and one of the fastest fixes. Windows installs with a specific storage controller mode — almost always AHCI for SATA drives, or the native NVMe stack for M.2 drives. Change that mode and Windows tries to load a driver that no longer matches the hardware it’s talking to, which produces exactly this BSOD.

Enter BIOS by pressing Del, F2, or F12 immediately when you see the manufacturer splash screen. Look for a section labeled “SATA Configuration,” “Storage,” or “Peripherals.” The specific setting may say SATA Mode, SATA Operation, or Controller Mode. You’re looking for a value like AHCI, IDE, RAID, Intel RST, or “RAID On.”

For virtually every Windows 11 installation, the correct mode is AHCI. If it says IDE, switch it to AHCI. If it previously said AHCI and now shows RAID (or vice versa) after a BIOS update, switch it back. Save and exit.

One thing I’ve run into on Intel 12th and 13th gen boards: a VMD (Volume Management Device) setting that’s enabled by default even on machines that don’t use hardware RAID at all. Disabling VMD on a system that was installed without it can break boot just as badly as the AHCI/IDE switch. The rule is to restore the exact configuration that was in place when Windows was first installed — don’t experiment with new settings while trying to recover.

Fix 2 — Run Startup Repair from WinRE

You need a Windows 11 USB drive for this. If you don’t have one, create it on a working machine at microsoft.com/software-download/windows11 using the Media Creation Tool.

Boot from the USB. When the “Install Windows” screen appears, click Repair your computer — not Install. Then navigate: Troubleshoot → Advanced Options → Startup Repair. Select your OS and let it run.

Try this before going manual. Startup Repair fixes a surprising number of BCD and boot-file problems automatically, and it’s fast. If it says “Startup Repair couldn’t repair your PC,” you can check the log from Command Prompt in WinRE:

type C:\Windows\System32\Logfiles\Srt\SrtTrail.txt

The log usually names the specific driver or file causing the failure, which points you directly at the right fix below.

Fix 3 — Repair the BCD Manually

From Advanced Options, open Command Prompt instead of Startup Repair.

Step 1: Run chkdsk

Drive letters shift in WinRE — C: often gets assigned to the recovery partition, and your Windows installation may be sitting on D:, E:, or something else. Confirm which drive actually has Windows on it:

dir C:\ dir D:\

Whichever one lists a Windows folder is your OS drive. Substitute that letter in every command that follows. Then run chkdsk against it:

chkdsk C: /f /r

The /f flag repairs filesystem errors; /r locates bad sectors and recovers readable data. On an HDD this can take 30–60 minutes; on an NVMe SSD it’s usually a few minutes. Let it finish before rebooting.

Step 2: Rebuild the BCD

Before choosing a command, establish whether you have a UEFI/GPT system or an older legacy BIOS/MBR system. Run diskpart:

diskpart list disk

If any disk shows an asterisk (*) under the GPT column, you’re on UEFI. That’s the case on virtually every Windows 11 machine sold in the last decade. Type exit to leave diskpart.

For UEFI/GPT systems (most Windows 11 machines):

Do not run bootrec /fixboot here. On UEFI/GPT disks it returns “Access is denied” and that’s entirely expected — there’s no traditional boot sector for it to write to. Use bcdboot instead, which is the right tool for EFI-based boot repair. First, find your EFI System Partition:

diskpart list vol

Look for a FAT32 partition roughly 99–500 MB in size with “System” in the Info column. That’s your EFI partition. Select it and assign a temporary drive letter (use any letter not already taken):

sel vol 2 assign letter=S exit

Replace 2 with your actual EFI volume number from list vol. Now copy fresh boot files from your Windows partition to the EFI partition and recreate the BCD:

bcdboot C:\Windows /s S: /f UEFI

Replace C: with your actual Windows drive letter. You should see “Boot files successfully created.” Reboot.

For MBR/legacy BIOS systems (older hardware):

Run these four commands in order:

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

If bootrec /rebuildbcd reports “Total identified Windows installations: 0,” the BCD is entirely gone. Also run bcdboot C:\Windows /f BIOS to recreate boot files from the Windows partition directly.

Fix 4 — Check the storahci or stornvme Registry Start Value

If the BSOD appeared right after a Windows Update and everything above hasn’t helped, the storage driver’s startup type may have been changed as a side effect of the update. Windows needs the storage driver loaded at boot, not on demand. A Start value of 3 (demand start) means the driver won’t load early enough — you get the BSOD. It needs to be 0 (boot start).

From WinRE Command Prompt, load the offline system hive and check (replace C: with your actual Windows drive letter if different):

reg load HKLM\TempSys C:\Windows\System32\config\SYSTEM reg query "HKLM\TempSys\ControlSet001\Services\storahci" /v Start

If the result shows Start = 0x3, that’s the problem. Set it to boot start:

reg add "HKLM\TempSys\ControlSet001\Services\storahci" /v Start /t REG_DWORD /d 0 /f

If your boot drive is NVMe (M.2), run the same fix against stornvme:

reg add "HKLM\TempSys\ControlSet001\Services\stornvme" /v Start /t REG_DWORD /d 0 /f

Then unload the hive and reboot:

reg unload HKLM\TempSys

If you want to do this on a working Windows machine before changing the BIOS storage mode — which is actually the smart time to do it — open an elevated Command Prompt and run sc config storahci start= boot. Note the space after the equals sign; that’s intentional syntax for the sc command.

Common Triggers and Fixes at a Glance

Trigger	Most Likely Cause	Fix
Right after Windows Update	storahci or stornvme startup type changed, or BCD corrupted	Startup Repair, then storahci registry fix (Fix 4)
After a BIOS update	SATA mode reset to IDE or RAID as “safe default”	Revert BIOS storage mode to AHCI (Fix 1)
After manually switching SATA mode	Driver/mode mismatch; Windows loaded wrong stack	Revert BIOS; or use sc config before switching next time
After moving drive to a new PC	Different storage controller; old driver doesn’t match new hardware	Startup Repair; may require a clean install
After adding a second drive	Boot order or BCD partition reference shifted	bcdboot or bootrec /rebuildbcd (Fix 3)
No obvious trigger	Corrupted BCD or filesystem damage	chkdsk, then BCD repair (Fix 3)

When None of This Works

If you’ve been through all four fixes and still can’t boot, check the hardware before reinstalling. Reseat the SSD or NVMe module in its slot — a loose connection after adding RAM or cleaning the machine is a more common cause than it should be. If you have a spare M.2 slot, try it there. Most SSD manufacturers (Samsung, Crucial, Western Digital, Seagate) offer bootable diagnostic utilities you can run from a separate USB drive independently of Windows.

If the drive checks out, an in-place upgrade is the right next step before a full clean install. Boot from the Windows 11 USB, click Install Now on the Setup screen, and choose Keep my files and apps when prompted. That rebuilds system files without wiping your data. Treat clean install as the last resort, not the first thing you reach for.

Microsoft’s official troubleshooting reference for stop error 7B is at MS Learn. It covers advanced scenarios including filter driver conflicts and corrupted component stores that go beyond what a typical BSOD warrants.

Frequently Asked Questions

Why does bootrec /fixboot say “Access is denied”?

On UEFI/GPT systems — which covers every modern Windows 11 machine — bootrec /fixboot has nothing to write to. UEFI machines don’t use a traditional boot sector; boot files live in the EFI partition and are managed by the firmware. “Access is denied” is the expected response on these systems, not a new problem. Use bcdboot as described in Fix 3.

Will these commands delete my files?

No. chkdsk, bootrec, and bcdboot don’t touch personal files. bcdboot only writes to the small FAT32 EFI partition, which holds no personal data. The registry fix edits one DWORD value in the system hive. The only steps in this guide that touch personal files are an in-place upgrade (which preserves them when you choose “Keep my files”) and a full clean install.

Can a BIOS update cause INACCESSIBLE_BOOT_DEVICE?

Yes, and it’s more common than most people expect. Some BIOS updates reset the SATA operation mode to IDE as a conservative default, breaking any Windows installation configured for AHCI. Enter BIOS and put the storage mode back to what it was before the update. Some Gigabyte and ASUS boards also silently enable Intel VMD in certain BIOS revisions, which has the same effect.

What if Startup Repair says it can’t fix my PC?

Read the repair log. From WinRE Command Prompt run type C:\Windows\System32\Logfiles\Srt\SrtTrail.txt. It identifies the root cause — typically a missing or corrupt boot file, a driver with an invalid start type, or a component-store issue — and tells you exactly which fix to apply. Don’t keep repeating Startup Repair hoping it will eventually work; the log gives you the actual answer.

My NVMe drive is invisible in diskpart. What’s going on?

If diskpart shows no drives at all, your NVMe may be behind an Intel VMD controller that requires its own driver before WinRE can enumerate the disk. Try disabling VMD in BIOS temporarily to see if the drive appears. If it does and you’re not using hardware RAID, leaving VMD off is fine — Windows doesn’t need it for a single-drive setup. If you require VMD for RAID, you’ll need to load the Intel RST VMD driver from your OEM’s support page during WinRE setup.

What does bootrec /scanos actually do?

It scans all attached disks for Windows installations and reports how many it finds. If it returns “Total identified Windows installations: 0,” the boot environment can’t see your OS at all — the BCD is entirely gone, the drive isn’t seated correctly, or the filesystem is too damaged to read. If you hit zero, skip straight to bcdboot to recreate the BCD from scratch rather than trying to rebuild one that isn’t there.