INACCESSIBLE_BOOT_DEVICE (0x0000007B) means Windows lost access to its system partition during startup. This guide applies to Windows 11 and Windows 10 PCs that show this exact stop code or enter a blue-screen restart loop before reaching the desktop. The safest first action is to stop repeated uncontrolled restarts, obtain the BitLocker recovery key, enter Windows Recovery Environment, and confirm that the startup disk is visible before repairing anything.

What INACCESSIBLE_BOOT_DEVICE (0x0000007B) means

INACCESSIBLE_BOOT_DEVICE, Inaccessible_Boot_Device, Stop error 7B, Stop code 0x7B, Bug check 0x7B, and 0x0000007B are variants of the same Windows startup failure. According to Microsoft’s INACCESSIBLE_BOOT_DEVICE bug-check reference, Windows has lost access to the system partition during startup.

Documented causes include storage-stack filter-driver problems, file-system or boot-partition corruption, a changed storage controller or firmware mode, faulty storage hardware, and, in unusual cases, pending update actions affected by component-store corruption. The code alone does not identify which cause applies, so disk visibility and the immediately preceding change determine the appropriate branch.

This procedure is limited to the exact 0x7B startup failure. It is not a general guide to blue screens, black screens, bootloader errors, or Windows Update failures.

Before repairing anything: protect recovery access and enter WinRE

Enter WinRE and protect recovery access

When this applies: Windows cannot reach the desktop or repeatedly restarts with INACCESSIBLE_BOOT_DEVICE.

Prerequisites: Obtain the BitLocker recovery key if device encryption is enabled. Prepare Windows installation media if automatic recovery does not appear. WinRE tools may require the recovery key.

  1. Allow automatic repair to appear after failed starts. If it does not, intentionally interrupt startup twice, then select Advanced options on the third start.
  2. Alternatively, start the PC from Windows installation media, select Next, and then select Repair my PC.
  3. Open Troubleshoot and then Advanced options.

Expected result: WinRE displays its recovery tools, including the tools needed for the remaining checks. Microsoft’s supported entry methods and BitLocker warning are documented in Microsoft’s Windows Recovery Environment guide.

Risk and rollback: Risk is low while only entering WinRE. Do not select Reset or reinstall Windows before assessing disk visibility, hardware condition, encryption access, and data-recovery needs.

Check whether WinRE can see the Windows disk

Verify that the OS disk and volumes are visible

When this applies: Always perform this read-only checkpoint before BCD, registry, file-system, or offline update repairs.

Prerequisites: First confirm whether the physical startup disk is detected in the PC’s firmware, using the manufacturer’s documentation for that device. Then open Command Prompt from WinRE. Remember that drive letters in WinRE can differ from those in the normal Windows session.

  1. Run diskpart.
  2. Run list disk and confirm that the operating-system disk is listed.
  3. Only after the disk is listed, run list vol.
  4. Identify the Windows, SYSTEM/EFI, recovery, and data volumes by their labels, file systems, sizes, and status. Do not identify them from assumed drive letters.
  5. Record the verified Windows and SYSTEM/EFI volume letters for any later procedure that needs them.

Expected result: The physical operating-system disk appears, and the relevant volumes can be distinguished without changing their contents. Microsoft’s advanced Stop error 7B procedure documents this diagnostic gate.

Risk and rollback: Risk is low because these commands inspect rather than modify storage. Do not use DiskPart commands that clean, initialize, format, create, delete, or repartition anything. If the operating-system disk is absent in firmware or list disk, stop: Windows-level repair is not appropriate.

Choose the recovery branch based on what changed

What immediately preceded the error Applicable branch
A Windows update, driver, software, or other recent system change With the disk visible, try Startup Repair. Then use System Restore if a suitable restore point exists, or Uninstall Updates if an update immediately preceded the failure.
A confirmed BIOS/UEFI storage-controller mode change, added controller, moved disk, or new storage hardware Record the current setting, then reverse only the confirmed change using the manufacturer’s documentation. Remove newly added storage hardware where applicable and run manufacturer diagnostics.
A cloned or migrated disk Confirm firmware and WinRE disk visibility, controller compatibility, and volume identity. Inspect BCD only if its entries are shown to be wrong; cloning alone does not prove a BCD defect.
A storage or filter-driver installation Use ordinary recovery tools first. Consider the advanced filter-driver branch only when evidence identifies a nonstandard third-party storage filter or boot-critical service problem.
File-system symptoms or no known change Use recovery tools first. Proceed to targeted integrity, BCD, or hardware checks only when the observed evidence supports that branch.

If Safe Mode is accessible and the trigger points to software or a driver, it can provide a conditional diagnostic context. This article does not prescribe a separate Safe Mode procedure.

Revert a confirmed storage-controller or hardware change

When this applies: A storage-controller mode change, added controller, moved disk, or newly installed storage hardware immediately preceded 0x7B.

Prerequisites: Record the current firmware setting before changing it and use the PC manufacturer’s documentation for its firmware controls.

  1. Remove recently added storage hardware or controllers where applicable.
  2. If a controller mode was changed, restore the prior setting.
  3. Confirm that the storage hardware and controller are compatible with the installed Windows version.
  4. Run the manufacturer’s hardware diagnostics and seek an appropriate firmware update where applicable.

Expected result: Windows again uses the storage configuration under which it previously started, or diagnostics identify a hardware condition requiring escalation.

Risk and rollback: Risk is medium. Restore the recorded setting if the reversal is incorrect. Do not switch AHCI, RAID, Intel RST, VMD, or other storage modes by trial and error, and do not make unrelated firmware changes.

Use Startup Repair, System Restore, or Uninstall Updates

Run the applicable WinRE recovery tool

When this applies: The operating-system disk is visible and the failure followed a recent startup, driver, software, or Windows update change.

Prerequisites: WinRE access and, when requested, the BitLocker recovery key. System Restore also requires a restore point created before the failure.

  1. From WinRE Advanced options, try Startup Repair.
  2. If Startup Repair does not restore startup and a suitable restore point exists, use System Restore and select a point from before the failure.
  3. If a Windows update immediately preceded INACCESSIBLE_BOOT_DEVICE, use Uninstall Updates from WinRE.
  4. Restart and reassess after each individual recovery action rather than running every option without testing.

Expected result: Windows may start after the relevant startup, system, or update change is reversed. If the exact stop code remains, return to WinRE and use only the advanced branch supported by the diagnostic evidence.

Risk and rollback: Risk is medium. System Restore reverses system changes. An uninstalled update can later be reinstalled. Do not proceed automatically to offline DISM merely because these recovery tools did not resolve an error that was unrelated to an update.

Use advanced repairs only when the diagnostic evidence matches

These branches require a visible disk, verified volume identities, and the BitLocker key where applicable. Never assume the offline Windows volume is C:. Microsoft’s exact advanced 7B article explicitly lists Windows 10; although current WinRE guidance covers Windows 11 and Windows 10, the following advanced branches should not be treated as validated identically on every Windows 11 build.

Revert pending update actions offline

When this applies: INACCESSIBLE_BOOT_DEVICE began immediately after a Windows update, and the disk and offline Windows volume have been confirmed.

Prerequisites: WinRE Command Prompt and the verified OS drive letter. Back up any loaded registry hive before editing it.

  1. Run DISM /Image:<OSDrive>: /Get-Packages.
  2. Check the output for packages marked Install Pending or Uninstall Pending.
  3. Run DISM /Image:<OSDrive>: /Cleanup-Image /RevertPendingActions.
  4. Restart and test Windows startup.
  5. Consider pending.xml or offline-registry work only if the documented DISM path does not restore startup, and follow Microsoft’s advanced procedure rather than improvising registry changes.

Expected result: Pending update actions are reverted so Windows can attempt startup without committing them.

Risk and rollback: Risk is high. The OS drive letter must be correct. Before deleting PendingXmlIdentifier or PendingFileRenameOperations values in any fallback registry procedure, back up the loaded hive so it can be restored.

Verify and repair BCD only when entries or boot files are wrong

When this applies: The disk is visible and bcdedit shows a missing or incorrect boot device, OS device, path, or systemroot entry.

Prerequisites: WinRE Command Prompt, confirmed OS and SYSTEM/EFI volume letters, and a destination for the BCD backup.

  1. Run bcdedit and inspect {bootmgr} and {default}.
  2. Export the current configuration first with bcdedit /export <backup-path>.
  3. Correct only the value proven to be incorrect, following Microsoft’s advanced Stop error 7B procedure.
  4. Use bootrec /rebuildbcd only when rebuilding the BCD is required.
  5. If boot files are missing, back up the SYSTEM contents before using bcdboot.

Expected result: Verified boot entries point to the correct visible Windows and system volumes.

Risk and rollback: Risk is high. Restore the export with bcdedit /import <backup-path> if necessary; importing it overwrites the current BCD settings. Do not run routine bootrec command lists or format the EFI partition.

Targeted offline integrity or filter-driver repair

When this applies: Disk visibility is confirmed and evidence points specifically to file corruption, a boot-critical service, or a nonstandard third-party storage filter driver.

Prerequisites: WinRE Command Prompt or Registry Editor, the verified OS drive letter, and a backup of registry values or loaded hives before any registry change.

  1. For suspected disk corruption, run chkdsk /f /r <OSDrive>:.
  2. Run sfc /scannow /offbootdir=<OSDrive>:\ /offwindir=<OSDrive>:\Windows.
  3. Inspect UpperFilters and LowerFilters only when evidence points to a nonstandard third-party storage filter.
  4. After creating a backup, delete only the specifically identified nonstandard filter value by following Microsoft’s documented offline procedure.
  5. Verify boot-critical service Start values only through the documented offline-hive procedure.

Expected result: The supported integrity checks repair identified corruption, or the documented filter procedure removes a proven third-party storage-stack obstruction.

Risk and rollback: Risk is high. Restore the backed-up registry value or hive if the change must be reversed. Do not remove unidentified filters, and do not disable a filter service without removing its corresponding filter entry through the documented procedure.

When to stop repairing and escalate

  • The disk is absent in firmware or DiskPart: Stop Windows repairs and contact the OEM, virtualization provider, or a qualified repair service.
  • The BitLocker recovery key is unavailable: Do not continue with offline recovery actions that require access to the encrypted volume.
  • Detection is intermittent or I/O errors recur: Treat this as possible SSD, controller, cable, or motherboard failure rather than continuing file repairs.
  • Manufacturer diagnostics fail: Escalate for hardware service.
  • Files are not backed up and hardware failure is suspected: Assess professional data recovery before CHKDSK, reset, reinstall, or other write-intensive actions.

Resetting or reinstalling Windows is a late option only after disk visibility, hardware condition, BitLocker access, backups, and data-recovery needs have been assessed. It can remove apps, settings, or files and will not repair an absent or failing physical disk.

If the failure occurs during Windows Setup or a feature upgrade and rolls back with 0xC1900101 rather than showing INACCESSIBLE_BOOT_DEVICE during ordinary startup, use the separate guide for Windows 11 upgrade rollback error 0xC1900101.