INACCESSIBLE_BOOT_DEVICE in Windows 11: how to fix it

Applies to: Windows 11 (and Windows 10) PCs that show the INACCESSIBLE_BOOT_DEVICE blue screen during startup, often followed by the Automatic Repair screen. Every step below can be done from recovery, without starting Windows. If you see a different stop code, our guide on finding and reading the stop code routes you to the right fix. If the PC only shows the Automatic Repair message and no 0x7B code, the Automatic Repair guide is the better starting point.

What INACCESSIBLE_BOOT_DEVICE means

Microsoft’s bug check 0x7B reference says this stop error means Windows “has lost access to the system partition during startup” and that it always happens while the system is starting. The boot manager has already loaded the core of Windows, but when Windows tries to take over the disk with its own storage driver, it either can’t talk to the controller or can’t read the file system on the partition.

Microsoft’s troubleshooting article for Stop error 7B lists the main causes: storage filter drivers that are missing, corrupted or misbehaving; file system corruption; a changed storage controller mode or BIOS setting; a different storage controller from the one Windows was installed with, including a disk moved to another PC; and faulty hardware. In rare cases, an update that couldn’t be committed is behind it. The bug check page adds that some disk controllers need extra drivers at startup, and that failed storage hardware can cause it too.

Because the error happens before Windows finishes loading, a single occurrence that never returns is not much to worry about. If it appears on every start, work through the fixes below in order. They run from changes that are easy to undo to ones that need care.

Match your symptom

What happened before the error	Likely cause	Start with
You changed BIOS/UEFI settings, reset them to defaults or updated the firmware	The storage controller mode no longer matches the driver Windows uses	Fix 2
You added, swapped or cloned a drive, or moved the drive to another PC	Wrong boot drive or a controller Windows has no driver for	Fix 1, Fix 2
Windows was installing an update, or the error began after one	A pending or incomplete update	Fix 4
Nothing changed, or the PC lost power	File system damage or a failing drive	Fix 3, Fix 5
Startup Repair runs but fails, or boot files are reported missing	Damaged boot configuration (BCD) or boot files	Fix 6
You installed storage, encryption or backup software that hooks into disks	A third-party filter driver	Fix 7
The drive doesn’t appear in recovery or in the firmware	Hardware, cable or controller fault	Fix 1, Fix 8

Before you start: recovery key, backup and WinRE

Find your BitLocker recovery key

Many Windows 11 PCs have BitLocker or device encryption turned on, often without the owner knowing. Microsoft’s BitLocker recovery overview lists changes that can make BitLocker ask for the 48-digit recovery password at the next start, including firmware upgrades, changes to the boot manager and, on older TPM 1.2 devices, changing the boot order. Microsoft also says that if you start recovery manually from a repair disk, you need the recovery key to unlock the drive. For a home PC signed in with a Microsoft account, the key is normally saved to that account; work and school PCs usually store it with the organization. Our guide to getting the key from your Microsoft account is written for Dell PCs, but the account steps are the same on any brand. Write the key down on another device before you change anything.

Protect your files

None of the early fixes delete personal files. Fixes 5 to 8 rewrite disk structures, boot files or the registry, and a reset or reinstall can remove data. If the files on this PC matter and you have no backup, consider copying them off first, for example by connecting the drive to another PC, or by booting a separate recovery tool that can read it. If the drive makes clicking noises or disappears and reappears, stop and copy data before running any repair; repeated scans can make a failing drive worse.

Open the Windows Recovery Environment

According to Microsoft’s WinRE technical reference, Windows opens WinRE automatically after two failed attempts to start, so a PC stuck on this error often lands on the blue Choose an option screen on its own. From there, go to Troubleshoot > Advanced options to find Startup Repair, Uninstall Updates, System Restore and Command Prompt. If it never reaches that screen, our WinRE guide shows how to open recovery when Windows won’t start, including from a USB installer made on another PC. Microsoft’s Stop error 7B article uses that route: boot from installation media, select Next, then Repair your computer.

In recovery, the Windows partition often isn’t drive C:. The commands below use C: as an example; Fix 5 shows how to find the right letter, and our offline SFC guide covers finding the Windows drive letter in more detail.

Fix 1: Undo recent hardware changes

Microsoft’s first suggestion when Windows won’t start is to revert recent hardware changes, especially new disks or controllers. This is safe and costs nothing to try.

1. Shut the PC down fully. Unplug USB drives, memory cards, docks and external disks, then start it again.
2. If you added an internal drive, disconnect it, or check in the firmware that the drive with Windows on it is still first in the boot order.
3. On a desktop, reseat the data and power cables of the Windows drive, or the M.2 drive itself, with the power cable removed. On a laptop, leave internal parts alone unless you’re comfortable with them and the warranty allows it.
4. If you cloned Windows to a new SSD, make sure only the new drive is connected for the first start, or boot from the old drive to confirm it still works.

A Windows drive moved from another PC is a special case. The new PC may use a storage controller Windows has no driver loaded for, which Microsoft lists as a direct cause. Unless the two PCs use the same controller mode, the reliable fix is usually a clean install on the new PC after copying your files.

Fix 2: Undo BIOS/UEFI storage settings

This is the most common cause after a firmware update, a CMOS reset or a change you made yourself. Windows loads only the storage driver for the controller mode it was set up with. If the firmware switches the SATA or NVMe controller to a different mode, Windows can’t find its own drive. Microsoft’s bug check page gives switching the controller from legacy mode to AHCI as an example of a change to revert.

Warning: changing firmware settings can trigger a BitLocker recovery prompt at the next start, so have the recovery key from the section above. Change only the storage setting described here, write down the old value first, and don’t try every mode in turn; each switch can make the next start fail in a different way.

1. Restart and enter the firmware setup. The key differs by maker; F2, Del, F10 or F12 are common. From the WinRE Advanced options screen, UEFI Firmware Settings opens it directly on many PCs.
2. Find the storage or SATA setting. Names vary: SATA Mode, SATA Operation, Storage Configuration, or an Intel VMD or Intel RST option on many recent Intel PCs.
3. Set it back to what it was when Windows was installed. If you don’t know, the value the PC shipped with is the best guess; on many laptops sold with Windows 11 that is RAID On or VMD enabled rather than AHCI.
4. Save, exit and let the PC try to start. If BitLocker asks for the key, enter it.

If you updated the firmware and the settings went back to defaults, the controller mode may have changed without you touching it. Compare the storage setting against any notes or photos of your old settings, or the maker’s support page for the model.

If you need to change the controller mode on purpose

Sometimes you want a different mode, for example AHCI for a dual-boot setup. Changing it first and then expecting Windows to start usually ends in this error. A widely used method, not described on the Microsoft pages fetched for this guide, is to make Windows start in Safe Mode once so it loads the generic storage drivers for the new mode. Microsoft’s bug check page does say that starting in Safe Mode and then normally lets the core storage drivers load again. Do this only from a working Windows, in an elevated Command Prompt, before you change the firmware:

bcdedit /set {current} safeboot minimal

Restart, change the mode in the firmware, and let Windows start in Safe Mode. Then, in an elevated Command Prompt in Safe Mode, remove the setting and restart normally:

bcdedit /deletevalue {current} safeboot

Forgetting the second command leaves the PC starting in Safe Mode every time. On a PC with BitLocker, suspend protection first; Microsoft’s recovery overview recommends suspending BitLocker before planned firmware changes.

Fix 3: Run Startup Repair

Startup Repair is the automatic tool in WinRE. It checks for common startup problems, such as damaged boot files, and fixes what it can. It doesn’t remove files or apps, so it’s worth a try before any manual commands.

1. In WinRE, select Troubleshoot > Advanced options > Startup Repair.
2. Choose your account and enter its password if asked, or enter the BitLocker recovery key.
3. Wait for it to finish, then restart.

If it reports that it couldn’t repair the PC, note any log file path it shows and move on. Our Automatic Repair guide explains what Startup Repair does and what its results mean.

Fix 4: Back out a stuck or recent update

If the error began right after Windows Update, or while an update was installing, remove the update first with the built-in tool. It’s simpler and safer than the manual steps below.

1. In WinRE, select Troubleshoot > Advanced options > Uninstall Updates.
2. Choose Uninstall latest quality update for a monthly update, or Uninstall latest feature update if the PC was moving to a new Windows version.
3. Restart and check whether Windows starts.

Our Automatic Repair guide has more on uninstalling the latest update from recovery, including which option to pick.

Revert pending update actions with DISM (advanced)

If the uninstall option fails or isn’t there, Microsoft’s Stop error 7B article gives a manual method. Open Troubleshoot > Advanced options > Command Prompt and list the update packages on the offline Windows drive:

dism /Image:C:\ /Get-Packages

If any show Install Pending or Uninstall Pending, revert them with the command from the same Microsoft article:

dism /Image:C:\ /Cleanup-Image /RevertPendingActions

Replace C: with the letter of the Windows partition in recovery. Microsoft then suggests renaming C:\Windows\WinSxS\pending.xml, if it exists, to pending.xml.old, and goes on to remove pending entries from the offline registry. The registry part is for confident users only; follow Microsoft’s article step by step and back up each key before deleting anything. Some updates can’t be uninstalled this way, and DISM may need the BitLocker drive unlocked first.

Fix 5: Check the disk and system files

Confirm recovery can see the drive

Microsoft’s first check in the 7B article is whether the boot disk is visible at all. In the WinRE Command Prompt, run these one at a time:

diskpart
list disk
list vol
exit

list disk should show your Windows drive, with an asterisk in the Gpt column on a UEFI PC. list vol shows the volumes and their letters: look for the largest NTFS volume, which is usually Windows, and a small FAT32 volume, which is usually the EFI system partition. Microsoft says the Windows volume should show Boot and the system volume System with a healthy status, though in WinRE those labels may sit on the recovery tools instead. If the drive isn’t listed, the cause is hardware, a cable, or a controller setting: go back to Fix 1 and Fix 2, then Fix 8. Microsoft’s advice at that point is to contact the PC maker.

If the Windows volume shows as RAW or has no file system, BitLocker may simply be locked. WinRE usually asks for the recovery key when you open Command Prompt; if you skipped that prompt, restart Command Prompt and enter the key.

Repair the file system and system files

Warning: on a drive you suspect is failing, copy important files off before you run a disk repair. chkdsk /r reads every sector and can take hours on a large hard drive. Let it finish; interrupting it can leave the file system worse off.

Microsoft’s article lists both commands below as the final checks. Use the Windows letter you found with list vol:

chkdsk C: /f /r

sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows

The first fixes file system errors and marks bad sectors; the second checks protected Windows files on the offline installation. Our offline SFC guide explains the results and how to repair the Windows image with DISM offline if SFC can’t fix everything.

Fix 6: Check and rebuild the boot configuration

The Boot Configuration Data (BCD) store tells the boot manager which partition holds Windows. Microsoft’s 7B article includes checking it, because a wrong entry can point Windows at a partition it can’t use. In the WinRE Command Prompt, run:

bcdedit

Under Windows Boot Manager, check that device and path point to the boot loader; on a UEFI PC Microsoft’s example path is \EFI\Microsoft\Boot\bootmgfw.efi. Under Windows Boot Loader, check that device, osdevice, path and systemroot point to the Windows partition, the winload file and the \Windows folder.

Warning: editing the BCD can make the PC stop starting in a different way, and on a BitLocker PC changes to the boot manager can trigger a recovery prompt. Export a backup first, as Microsoft’s article does, and keep the folder name you use.

mkdir C:\temp
bcdedit /export C:\temp\bcdbackup

Microsoft’s article offers three repairs, from smallest to largest. To correct one value, for example the Windows partition of the default entry:

bcdedit /set {default} device partition=C:

To rebuild the store, which the article recommends if you see “The boot configuration data store could not be opened”:

bootrec /rebuildbcd

If the boot files themselves are missing, Microsoft’s article re-creates them with bcdboot, pointing at the Windows folder and the system partition. In the example below, S: is the EFI system partition; it often has no letter in WinRE, so you may need to assign one in diskpart with select vol followed by the volume number and assign letter=S. Microsoft’s article backs up the system partition’s contents before this step.

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

To undo your BCD changes, Microsoft’s article restores the export with bcdedit /import C:\temp\bcdbackup. Note that it replaces all current BCD settings. Some guides also suggest bootrec /fixmbr and bootrec /fixboot; those aren’t in Microsoft’s 7B article, and on current UEFI PCs bootrec /fixboot can fail with “Access is denied”, so the bcdboot step is the more direct repair.

Fix 7: Check boot drivers in the offline registry

This fix is for confident users, or for when nothing above worked and the error started after you installed disk, encryption, backup or antivirus software. Microsoft’s 7B article explains how a missing boot driver or a leftover third-party filter driver can produce the error.

Warning: editing the offline registry can make Windows unbootable if you change the wrong value. Back up each key before you change it (in Registry Editor, File > Export), change only the values described, and always unload the hive when you’re done.

1. In the WinRE Command Prompt, type regedit and press Enter.
2. Select HKEY_LOCAL_MACHINE, then File > Load Hive. Open C:\Windows\System32\config\SYSTEM and name it OfflineSystemHive.
3. Open OfflineSystemHive\Select and note the Default value. If it’s 1, work in ControlSet001; if 2, ControlSet002.
4. Under that control set’s Services key, Microsoft says these keys should exist and have Start set to 0: ACPI, DISK, VOLMGR, PARTMGR, VOLSNAP and VOLUME.
5. Under the control set’s Control\Class key, check the UpperFilters and LowerFilters values in the disk and storage classes Microsoft names, including {4D36E967-E325-11CE-BFC1-08002BE10318} (disk drives) and {4D36E96A-E325-11CE-BFC1-08002BE10318} (storage controllers). Microsoft’s advice is to remove only non-standard entries, ideally after comparing with a working PC, and to leave Windows entries such as PartMgr alone.
6. Select OfflineSystemHive, then File > Unload Hive, close Registry Editor and restart.

Microsoft adds a specific trap: if you disable a filter driver’s service without removing its UpperFilters or LowerFilters entry, Windows can crash with this same 0x7B error. Remove the filter entry, not just the service. The article also mentions restoring the SYSTEM hive from the RegBack folder if a key is missing; on many current PCs that folder is empty, so check the file sizes before you rely on it.

Fix 8: Firmware, hardware tests, restore or reinstall

Update firmware and check the drive

Microsoft’s bug check page suggests updating the UEFI (BIOS) and the storage controller firmware, and running the PC maker’s hardware diagnostics. Many PCs include a diagnostic tool in the firmware or a pre-boot menu; check the maker’s support page for the key. A failing drive test means the drive needs replacing, and further repairs on it put data at risk. If you update the firmware, check the storage mode afterwards (Fix 2), since an update can reset it.

System Restore

If restore points exist, Troubleshoot > Advanced options > System Restore rolls back system files, drivers and settings without touching personal files. Microsoft’s bug check page lists it as a fix for this error. Choose a restore point from before the error first appeared.

Reset or reinstall Windows

Warning: Reset this PC with Remove everything, or a clean install, deletes your files. Even Keep my files removes installed apps. Copy anything you need first, and note that a reset can fail too if Windows still can’t reach the drive.

If the drive passes its tests but nothing else works, Troubleshoot > Reset this PC reinstalls Windows. Microsoft’s bug check page also suggests creating installation media with the Media Creation Tool on another PC and doing a clean install, changing the boot order in the firmware if needed. On PCs with Intel VMD or RAID enabled, Windows Setup may not see the drive without the maker’s storage driver; load it from a USB stick with Load driver during setup, or get it from the PC maker’s support page.

Known issues

As of November 2026, Microsoft’s release health pages for Windows 11, version 25H2 and version 24H2 list no open or resolved known issue that causes INACCESSIBLE_BOOT_DEVICE. If the error appeared straight after an update on several PCs at once, check those pages again, since Microsoft posts confirmed problems and workarounds there first.

Related guides

• WinRE: what the Windows Recovery Environment is and how to open it
• Your PC couldn’t start properly: 7 fixes for the Automatic Repair screen
• SFC offline: how to run sfc /scannow from recovery in Windows 11 and 10
• Dell BitLocker recovery key: where to find it and why it appears
• Your PC ran into a problem and needs to restart: how to fix it

Official sources

• Microsoft: Advanced troubleshooting for Stop error 7B or Inaccessible_Boot_Device
• Microsoft: Bug check 0x7B INACCESSIBLE_BOOT_DEVICE
• Microsoft: BitLocker recovery overview