Inaccessible Boot Device (0x7B): Get Windows 11/10 Starting Again

INACCESSIBLE_BOOT_DEVICE (bug check 0x7B) means Windows started loading and then lost access to the drive it was loading from. Either the boot driver for the disk controller couldn’t talk to the drive, or the file system on it couldn’t be recognized. It always happens during startup, which is why the PC usually ends up restarting in a loop or sitting on Automatic Repair.

It often follows a change, such as a BIOS update or reset that switched the storage controller mode, a new or cloned SSD, or an update that didn’t finish installing. A drive that’s starting to fail can cause it too. Work out what changed in the last day or two before you touch anything.

Before any repair, find your BitLocker recovery key. Firmware changes and recovery tools can both trigger a BitLocker prompt, and without the key the data on an encrypted drive can’t be reached.

Before you change anything: BitLocker and your data

Windows 11 PCs are often encrypted with BitLocker or device encryption, sometimes without the owner realizing it. Microsoft lists firmware upgrades, changes to the boot manager, changes to the partition table and moving the drive to another computer among the events that trigger a recovery prompt, and recovery tools started from repair media need the key before they can read the drive.

• Get the 48-digit recovery key first: from the Microsoft account the PC was set up with, from your work account or IT admin (Microsoft Entra ID or Active Directory), or from a printout. Our BitLocker recovery key guide covers every place it can be.
• If you can’t find the key, don’t experiment with resets, partition tools or reinstalls. Without the key, encrypted data can’t be recovered.
• Write down any BIOS setting before you change it, so you can put it back.

What changed? Match the trigger to the fix

Microsoft’s causes for 0x7B include a changed storage controller mode, a different controller or a moved drive, storage filter drivers, file system or SYSTEM boot partition corruption, updates that failed to commit, and faulty hardware. Match them to what happened on this PC:

Step 1: Confirm the drive is still there

Open the BIOS/UEFI setup. The key varies by maker; Microsoft lists Esc, Del and F2 as common setup keys and F12, Esc, F9, F10 and F8 for boot menus, so check your PC’s documentation. From the recovery environment you can also use Troubleshoot > Advanced options > UEFI Firmware Settings.

If the system drive isn’t listed anywhere in the firmware, Windows isn’t the problem: it’s the drive, its connection or the controller. Storage listings vary by maker, so check the storage and boot sections before concluding it’s gone.

If the drive is listed, open Command Prompt in the recovery environment and run diskpart, then list disk and list vol, then exit. You should see the Windows volume (usually the largest; NTFS, though a BitLocker-locked volume may show RAW or no file system until it’s unlocked) and a small FAT32 boot volume, often labeled SYSTEM. manage-bde -status shows whether the Windows volume is BitLocker-locked.

Working from a Windows installation USB instead

If the PC never reaches the recovery screens, make Windows installation media on another computer and start the PC from it. Choose Repair your computer (Repair my PC on newer media), then Troubleshoot > Advanced options > Command Prompt. Pressing Shift+F10 on the first setup screen also opens a command prompt.

One trap before you blame the drive: on many PCs with Intel 11th-generation or newer processors, the SSD sits behind Intel VMD (shown in the BIOS as RAID, RST or VMD). Standard Windows media may not include that driver, so list disk can show no drive even when it’s healthy. Copy the Intel Rapid Storage Technology (RST) driver for your model from the PC maker’s support site to the USB stick, extract it, run drvload with the full path to its .inf file, then run list disk again. Dell notes that media made with its OS Recovery Tool avoids this.

Step 2: Put the storage controller mode back

Windows only prepares the boot driver for the controller mode it was set up on. Many business laptops ship with the controller in a RAID, Intel RST or VMD mode; a BIOS update or a reset to defaults can switch it to AHCI, or the other way round, and the next start ends in 0x7B. Microsoft’s first recommendation for this stop code is to revert recent UEFI changes like this one.

1. In the BIOS/UEFI setup, find the storage or SATA operation setting. The name and location vary by maker and model.
2. Set it back to its previous value, save and restart. Expect a BitLocker prompt and enter the key.
3. If you don’t know the previous value, try the other mode once. If that doesn’t help, put it back to what it showed when you started.

If you need to change modes on purpose

For a planned switch to AHCI on a PC that starts normally: suspend BitLocker for several restarts (in an administrator PowerShell window, Suspend-BitLocker -MountPoint C: -RebootCount 3), then in the same window run bcdedit /set "{current}" safeboot minimal. PowerShell needs the quotes around {current}. Restart into the firmware and change the mode, then let Windows start in Safe Mode, which loads the built-in AHCI driver. Once in Safe Mode, run bcdedit /deletevalue "{current}" safeboot the same way and restart normally. Don’t attempt this on a PC that’s already failing to start.

If it started after cloning to a new SSD

Keep the old drive untouched as a fallback, and work through these in order.

1. Start the clone with the old drive disconnected. With both drives attached, the PC can load boot files from the old drive and Windows from the new one. If the new drive starts only while the old one is connected, it’s borrowing the old drive’s boot files; the last step fixes that.
2. Try one Safe Mode start, then a normal restart. Moving Windows from a SATA SSD to an NVMe SSD, or into a different PC, puts it on a storage controller it wasn’t set up to start from. Safe Mode loads a core set of storage drivers and can get the next normal start working.
3. Check the partitions and rebuild the boot files. With the old drive still disconnected, run diskpart, list vol and exit in the recovery Command Prompt. If the new drive has no small FAT32 boot volume, the tool cloned only the Windows partition: re-clone the whole disk with the SSD maker’s migration tool. If the boot volume is there, run bcdboot C:\Windows (using the Windows volume’s letter), which rebuilds the boot files and boot store on the system partition from that Windows folder.

Step 3: Recovery Environment repairs, in order

1. Startup Repair runs automatically after two failed starts. Let it finish once.
2. Safe Mode: Startup Settings > Restart, then 4. Microsoft notes that Safe Mode loads a core set of storage drivers, and a successful Safe Mode start followed by a normal restart can clear the problem.
3. Uninstall Updates, if it started right after an update: the latest quality update first.
4. System Restore to a point before the problem.

From the Command Prompt

Drive letters in the recovery environment often differ from normal; use the letter list vol showed for the Windows volume (C: below). Unlock BitLocker first if needed with manage-bde -unlock C: -RecoveryPassword followed by the key.

• Unfinished update: dism /Image:C:\ /Get-Packages lists installed packages. If any show Install Pending or Uninstall Pending, run dism /Image:C:\ /Cleanup-Image /RevertPendingActions. If C:\Windows\WinSxS\pending.xml still exists, Microsoft’s procedure renames it (ren C:\Windows\WinSxS\pending.xml pending.xml.old) and also deletes the PendingXmlIdentifier entry from the offline COMPONENTS hive (C:\Windows\System32\config\COMPONENTS). Load it like the SYSTEM hive in the advanced section below, and export it first.
• File system: chkdsk C: /f repairs file system errors. Microsoft’s procedure adds /r to look for bad sectors; on a drive you suspect is failing, get the data off first, because /r reads every sector.
• System files: sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows.
• Boot configuration: bcdedit should show a {bootmgr} entry and a {default} entry whose device and osdevice point to the Windows partition. Export a backup before changing anything (bcdedit /export C:\bcdbackup). If the entries are wrong or missing, bcdboot C:\Windows recreates the boot files and store from your Windows folder; if the store can’t be opened at all, Microsoft’s procedure uses bootrec /rebuildbcd.

If these send you back to Automatic Repair every time, see our automatic repair loop guide. For reading stop codes and crash logs once Windows is running again, see the blue screen of death guide.

Advanced: boot drivers and leftover filter drivers

This edits the offline registry. Export each key before you change it (File > Export), change only what’s described here, and stop if anything doesn’t match.

In the recovery Command Prompt, type regedit, select HKEY_LOCAL_MACHINE, and use File > Load Hive to open C:\Windows\System32\config\SYSTEM under a temporary name such as OfflineSystem. The Default value under Select tells you which ControlSet00x is active.

• Boot-critical services: under Services, the keys ACPI, disk, volmgr, partmgr, volsnap and volume should exist with Start set to 0.
• Filter drivers: under Control > Class, the storage classes {4D36E967-E325-11CE-BFC1-08002BE10318} (disk drives), {4D36E96A-E325-11CE-BFC1-08002BE10318} (IDE ATA/ATAPI controllers), {4D36E97B-E325-11CE-BFC1-08002BE10318} (storage controllers) and {71A27CDD-812A-11D0-BEC7-08002BE2092F} (volumes) may carry UpperFilters or LowerFilters values. Remove only a non-Microsoft entry left by encryption, backup or storage software that’s no longer installed. Windows’ own entries stay: on a current Windows 11 PC, typically partmgr and EhStorClass under disk drives, and volsnap, fvevol, iorate and rdyboost under volumes. fvevol is BitLocker’s own driver; never remove it. If you can’t identify an entry, compare the same key on a similar working PC, as Microsoft recommends, and leave anything you’re unsure of.

One trap Microsoft calls out: disabling a filter driver’s service without removing its filter entry causes 0x7B by itself. Remove the entry, not just the service. When you’re done, select the loaded hive and choose File > Unload Hive.

When it’s hardware, and when to stop

• The drive doesn’t appear in the BIOS/UEFI setup, or in list disk from the PC’s own recovery environment (or from installation media after loading the Intel RST/VMD driver, if your PC uses one).
• chkdsk reports bad sectors, the drive clicks, or it had been working only intermittently.
• 0x7B persists after reverting every change and running the repairs above.

At that point protect the data before anything else, and don’t run repeated chkdsk /r passes on a dying drive. Copy or image what you can, with the BitLocker key in hand, and only then replace the drive and reinstall Windows. Reseating or replacing an internal drive is hands-on work for a local technician or, if the PC is under warranty, the manufacturer’s repair service. Once Windows starts again, follow-up checks can be done through remote support, in a session you approve. Afterward, put a proper backup and restore setup in place so a future drive failure doesn’t take your files with it.

Common questions

Can I fix inaccessible boot device without losing data?

Usually. Reverting a BIOS change, Startup Repair, Safe Mode and Uninstall Updates leave your personal files in place, and System Restore keeps your files but removes apps and drivers installed after the restore point. chkdsk recovers only what it can still read from damaged areas, so copy data off a suspect drive first. The other real risk is a BitLocker-encrypted drive without its recovery key, so find the key before anything else.

Why did inaccessible boot device start after a BIOS update?

An inaccessible boot device after an AHCI or RAID mode change is common, because BIOS updates and resets can return settings to factory defaults, including the storage controller mode. If Windows was installed with the controller in RAID, Intel RST or VMD mode and it’s now in AHCI, or the reverse, Windows can’t load the right boot driver. Set the mode back to its previous value and expect a BitLocker recovery prompt afterward.

Why do I get inaccessible boot device after cloning to a new SSD?

Either the clone didn’t copy every partition and boot file correctly, or the new drive sits on a controller Windows has no boot driver for. Refit the old drive to confirm it still starts, then re-clone with the SSD maker’s migration tool, or repair the boot files from the recovery environment. Keep the old drive untouched until the new one works.

Will Startup Repair fix inaccessible boot device?

Sometimes, mainly when boot files or a driver can be identified from logs. It can’t undo a changed BIOS storage mode or fix a failing drive. Let it run once, then move on: revert recent BIOS changes, try Safe Mode, uninstall the latest update, and use the command-prompt checks for pending updates and disk errors.

Does inaccessible boot device mean my SSD is dead?

Not necessarily. It often follows a change such as a BIOS reset, an update or a clone. It points to the drive when the BIOS doesn’t list it, chkdsk finds bad sectors, or the problem appeared with no change at all. If the BIOS lists the drive but diskpart can’t see it, suspect a missing storage driver first. If you suspect the drive, stop repairs and get the data copied first.

Will resetting or reinstalling Windows fix inaccessible boot device?

Sometimes, but it should be the last step. If a changed BIOS storage mode or a bad clone is the cause, putting the setting back or rebuilding the boot files usually fixes it without losing anything, while a reset costs you your apps. Reset this PC also needs the recovery environment to reach the drive, and no reinstall fixes a failing drive. If you do reinstall, copy your files off first and have the BitLocker key ready.

Can I fix inaccessible boot device without a Windows USB?

Often, yes. When Windows fails to start several times, it opens the recovery environment by itself, and you can force it by interrupting startup with the power button twice; the third start should show the repair screens. Undoing a BIOS/UEFI change needs no media at all. You need a Windows installation USB, made on another PC, only when the recovery environment won’t load or can’t see the drive.