INACCESSIBLE_BOOT_DEVICE is a Windows Blue Screen of Death (BSOD) error that occurs when Windows loses access to the disk or partition containing the operating system during startup.

The classic bug check associated with this condition is:

Bug Check: 0x0000007B

Stop Code: INACCESSIBLE_BOOT_DEVICE

Microsoft describes bug check 0x7B as a condition in which Windows has lost access to the system partition during startup.

In simple terms, Windows begins loading but cannot continue communicating correctly with the SSD, NVMe drive, hard disk, storage controller, or system partition required to complete the boot process.

A typical computer may display:

Your device ran into a problem and needs to restart.

Stop code: INACCESSIBLE_BOOT_DEVICE

The computer may then restart repeatedly, enter Automatic Repair, or remain trapped in a BSOD boot loop.

How Serious Is INACCESSIBLE_BOOT_DEVICE?

This error should be treated seriously because Windows cannot reliably access its boot storage.

However, it does not automatically mean that your SSD or hard disk has failed.

The problem can be caused by:

• Incorrect BIOS/UEFI storage settings
• AHCI/RAID/VMD mode changes
• Corrupted or incompatible storage drivers
• Windows Update problems
• SSD or NVMe migration
• Disk cloning
• Motherboard replacement
• Storage controller changes
• Boot configuration corruption
• File-system corruption
• Firmware problems
• Loose storage connections
• Actual SSD/HDD failure

Microsoft specifically identifies boot-device failure, storage-driver initialization problems, repartitioning, BIOS configuration changes, disk-controller changes and storage hardware failure among possible causes.

Common Causes of INACCESSIBLE_BOOT_DEVICE

1. SATA Mode Changed in BIOS/UEFI

This is one of the most important things to check.

A computer may have originally been configured using:

• AHCI
• RAID
• Intel RST
• IDE/Legacy mode on older systems
• Intel VMD on certain newer systems

If Windows was installed while the controller was configured for one mode and BIOS is later changed to another, Windows may no longer have the appropriate boot-critical storage driver available.

For example:

Before: RAID On

After: AHCI

or:

Before: AHCI

After: RAID/RST

The result may be:

INACCESSIBLE_BOOT_DEVICE

Microsoft specifically recommends reverting recent UEFI/BIOS controller-mode changes when troubleshooting bug check 0x7B.

2. Windows Update or Driver Update

The problem may appear immediately after:

• Windows cumulative update
• Feature update
• Storage driver update
• Intel Rapid Storage Technology update
• Chipset update
• NVMe driver update
• Manufacturer driver update

A damaged or incompatible boot-critical storage driver can prevent Windows from accessing the system volume during startup.

3. SSD or HDD Cloning

The error is frequently encountered during migrations such as:

HDD → SSD

SATA SSD → NVMe SSD

Old PC → New PC

Physical PC → Virtual Machine

One storage controller → another controller

Although all Windows files may have been successfully cloned, Windows may not have the required boot-critical driver for the new storage environment.

4. Motherboard or Storage Controller Replacement

Changing a motherboard can introduce a completely different:

• SATA controller
• NVMe controller
• RAID controller
• Chipset
• VMD configuration

Windows may therefore be unable to communicate with the existing boot disk.

Microsoft also documents situations where changing boot-critical hardware configurations can lead to STOP 0x7B because a driver required under the new configuration isn't configured to load during startup.

5. SSD, NVMe or HDD Failure

A failing drive can cause Windows to lose access to the operating-system partition.

Possible warning signs include:

• SSD intermittently disappears from BIOS
• Very slow startup before the failure
• Frequent disk-related errors
• File corruption
• System freezing
• SMART warnings
• Clicking sounds from mechanical HDDs
• Windows repeatedly entering Automatic Repair
• Drive sometimes detected and sometimes missing

If the storage device is not detected in BIOS/UEFI, Windows repair commands are unlikely to solve the underlying hardware problem.

6. Corrupted File System

An unexpected shutdown, power failure, storage failure or other disk problem may damage NTFS structures.

Windows may then have difficulty mounting or accessing the operating-system volume.

7. Damaged Boot Configuration

Problems involving the following may contribute to Windows startup failure:

• Boot Configuration Data (BCD)
• EFI System Partition
• Windows Boot Manager
• Boot files
• System partition

Although BCD corruption does not cause every INACCESSIBLE_BOOT_DEVICE case, the boot environment should be checked when standard storage troubleshooting does not resolve the problem.

8. BIOS/UEFI Update

A BIOS update may reset configuration settings to their defaults.

For example, the machine previously used:

RAID / Intel RST

but after a BIOS update it changes to:

AHCI

or vice versa.

The SSD is still physically present, but Windows is now attempting to access it through a different controller configuration.

9. Intel VMD Configuration Changes

Many modern Intel-based laptops use Intel Volume Management Device (VMD) technology.

Depending on the computer configuration, changing VMD-related settings can change how Windows sees the NVMe storage controller.

If Windows was installed with the VMD/RST driver active and the BIOS storage configuration is later changed, startup problems can occur.

Do not randomly enable or disable VMD. First determine the configuration under which Windows was originally installed.

10. Loose or Faulty Storage Connection

On desktop computers and serviceable laptops, check:

• SATA data cable
• SATA power cable
• M.2 NVMe seating
• M.2 SATA seating
• RAID/SAS controller connection
• Backplane connection

A partially connected drive can sometimes be detected but still fail under actual I/O activity.

Troubleshooting INACCESSIBLE_BOOT_DEVICE

Troubleshoot the problem in stages rather than immediately reinstalling Windows.

Step 1: Identify What Changed

Before modifying anything, ask:

• Did the problem start after Windows Update?
• Was BIOS updated?
• Were BIOS defaults loaded?
• Was SATA mode changed?
• Was RAID changed to AHCI?
• Was VMD enabled or disabled?
• Was the SSD cloned?
• Was Windows moved to another PC?
• Was the motherboard replaced?
• Was a new SSD installed?
• Was a storage driver updated?
• Did the PC lose power unexpectedly?

The answer often determines the quickest repair.

Step 2: Check Whether the Boot Drive Is Detected in BIOS

Enter BIOS/UEFI setup.

Common setup keys include:

F2, Delete, Esc, F10

The exact key depends on the manufacturer.

Look under sections such as:

• Storage
• NVMe Configuration
• SATA Configuration
• System Information
• Boot
• Intel Rapid Storage Technology

Verify that the Windows SSD/HDD is detected.

If the drive is NOT detected

Do not begin by repairing Windows.

Instead check:

• SSD/HDD connection
• M.2 seating
• SATA cable
• SATA power
• Different SATA port
• Storage controller
• SSD/HDD health

If possible, test the disk in another computer or appropriate enclosure.

If the drive IS detected

Continue with Windows/BIOS troubleshooting.

Step 3: Check SATA/AHCI/RAID/VMD Configuration

Look at the BIOS storage configuration.

Possible settings include:

• AHCI
• RAID
• RAID On
• Intel RST
• VMD
• Legacy
• IDE

If the problem started immediately after a BIOS change, restore the previous configuration.

Example:

If Windows worked with:

SATA Operation = RAID On

and the setting was changed to:

AHCI

change it back to RAID On and test Windows.

Do not randomly switch storage modes on a production computer. The correct setting depends on how Windows was originally installed and which boot-critical drivers are available.

Step 4: Disconnect Unnecessary Storage Devices

Temporarily disconnect:

• External USB drives
• Additional SATA disks
• USB card readers
• Newly installed SSDs
• External docking stations

Leave only the Windows boot drive connected when practical.

This helps eliminate boot-order and controller conflicts.

Step 5: Enter Windows Recovery Environment

If Windows repeatedly fails to start, access Windows Recovery Environment (WinRE).

Microsoft notes that Windows can automatically enter recovery after repeated interrupted/failed startup attempts.

You can also boot from compatible Windows installation media and select:

Repair your computer

Then navigate to:

Troubleshoot → Advanced options

Step 6: Run Startup Repair

Go to:

Troubleshoot → Advanced options → Startup Repair

Startup Repair attempts to identify and repair several startup-related problems, including damaged system files, BCD problems and some incompatible-driver conditions.

Allow the process to complete and restart the computer.

Step 7: Try Safe Mode

Navigate to:

Troubleshoot → Advanced options → Startup Settings → Restart

Then choose:

4 – Enable Safe Mode

or:

5 – Enable Safe Mode with Networking

Safe Mode loads Windows using a reduced set of essential drivers and services.

This is particularly relevant to STOP 0x7B. Microsoft documents that Safe Mode can restore certain boot-driver Start Type settings after critical hardware reconfiguration.

If Windows successfully starts in Safe Mode, restart normally and test again.

Step 8: Remove a Recently Installed Windows Update

If INACCESSIBLE_BOOT_DEVICE started immediately after Windows Update, use WinRE.

Navigate to:

Troubleshoot → Advanced options → Uninstall Updates

You may see:

Uninstall latest quality update

and/or:

Uninstall latest feature update

Start with the update most closely associated with the beginning of the problem.

Step 9: Use System Restore

If System Restore was enabled before the problem occurred:

Troubleshoot → Advanced options → System Restore

Select a restore point created before the boot failure.

This can be useful when the problem started after:

• Driver installation
• Software installation
• Registry modification
• Windows configuration changes

Personal files are normally not the target of System Restore, but important data should always be backed up whenever possible before performing major recovery work.

Step 10: Check the Windows Partition from Command Prompt

Open:

Troubleshoot → Advanced options → Command Prompt

Important: Windows may not be C: inside WinRE.

Check available volumes:

diskpart
list volume
exit

Then test likely partitions:

dir C:\Windows

If Windows isn't there, try:

dir D:\Windows

or:

dir E:\Windows

Continue only after identifying the actual Windows partition.

Step 11: Check the File System

Suppose Windows is located on C:.

Run:

chkdsk C: /f

For a more intensive scan when disk damage is suspected:

chkdsk C: /f /r

Be aware that /r can take a considerable amount of time, especially on large or problematic drives.

If a drive appears to be physically failing and contains important data, prioritize data recovery/backup before repeatedly running intensive repair operations.

Step 12: Run Offline System File Checker

If Windows is installed on C:, an offline SFC repair can be attempted using the appropriate Windows and boot paths.

A commonly used form is:

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

However, WinRE drive letters and the location of the actual system/EFI partition vary between machines.

Do not blindly assume C: is correct.

Step 13: Inspect Boot Configuration

Run:

bcdedit

Review entries including:

• Windows Boot Manager
• Windows Boot Loader
• device
• osdevice
• path
• systemroot

For the installed Windows loader, systemroot will normally reference:

\Windows

Incorrect boot entries may require BCD repair.

Step 14: Rebuild Windows Boot Files with BCDBoot

On modern UEFI computers, BCDBoot is often more relevant than blindly applying older MBR repair commands.

First identify the Windows partition.

For example:

dir C:\Windows

Then identify the EFI System Partition using DiskPart.

diskpart
list volume

The EFI partition is normally a relatively small FAT32 partition.

Select the correct EFI volume:

select volume X

Assign a temporary letter:

assign letter=S
exit

Then rebuild UEFI boot files:

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

Replace C: with the actual Windows partition identified earlier.

Restart and test.

Warning: Selecting the wrong system partition can create additional boot problems. This procedure should be performed by an experienced technician when the partition layout is uncertain.

Step 15: Check BitLocker Status

Some Windows systems use BitLocker or Device Encryption.

In WinRE, the operating-system volume may be locked.

Check:

manage-bde -status

If the Windows partition is locked, you may need the BitLocker recovery key before accessing or repairing it.

Microsoft also notes that recovery tools such as Startup Repair may require the BitLocker key on encrypted systems.

Do not format or delete an encrypted partition simply because it appears inaccessible.

Step 16: Check Storage Drivers

Storage drivers are especially important when the system uses:

• Intel RST
• Intel VMD
• AMD RAID
• SAS controllers
• Hardware RAID
• Manufacturer-specific NVMe/storage controllers

A driver required to access the operating-system volume must be available early enough in the Windows boot process.

Microsoft's Windows startup troubleshooting guidance includes investigation of storage drivers and filter drivers for STOP 0x7B scenarios.

If the problem appeared after a driver update, consider:

• Safe Mode
• Driver rollback
• System Restore
• Uninstalling the problematic update
• Restoring the original storage-controller configuration

Step 17: Check SSD/HDD Health

If Windows repair repeatedly fails, investigate the physical drive.

Check:

• SMART status
• Manufacturer diagnostics
• BIOS diagnostics
• SSD firmware
• Read errors
• Bad sectors
• NVMe health information

Examples of manufacturer diagnostic environments may be available from the computer or drive manufacturer.

A disk that repeatedly disappears from BIOS should be treated primarily as a hardware/storage problem rather than a Windows boot-file problem.

Special Scenario: Error After Changing RAID to AHCI

Suppose the computer originally worked using:

RAID On

Someone changes BIOS to:

AHCI

Windows immediately shows:

INACCESSIBLE_BOOT_DEVICE

The first troubleshooting step should generally be to restore the original RAID On setting.

If Windows then starts, you have identified the configuration mismatch.

Do not reinstall Windows simply because switching controller modes caused a BSOD.

Special Scenario: Error After BIOS Update

A BIOS update may reset storage configuration.

Check:

BIOS → Storage/SATA Operation

Compare:

• AHCI
• RAID
• Intel RST
• VMD

Restore the configuration Windows previously used.

Also check the boot mode.

Modern Windows installations commonly use:

UEFI

Changing an existing UEFI installation to incompatible Legacy/CSM settings can create additional startup problems.

Special Scenario: Error After Cloning HDD to SSD

If Windows was cloned to another disk:

1. Disconnect the original drive temporarily.
2. Confirm the new SSD is detected in BIOS.
3. Confirm BIOS boot order.
4. Check whether the clone included the EFI/System partitions.
5. Check AHCI/RAID/VMD configuration.
6. Enter WinRE.
7. Identify the Windows partition.
8. Repair the boot environment if necessary.
9. Verify that Windows has the required storage-controller driver.

A successful copy of C: alone does not necessarily mean the new disk contains everything required for UEFI startup.

Special Scenario: SATA SSD to NVMe Migration

Migrating from SATA to NVMe changes the storage path substantially.

Check:

• Whether BIOS detects the NVMe SSD
• Whether the M.2 slot supports the installed SSD type
• UEFI configuration
• VMD/RST configuration
• EFI System Partition
• Boot files
• Required storage drivers

Also verify motherboard compatibility. Some M.2 slots support only NVMe, some support SATA, and some support both.

Special Scenario: Motherboard Replacement

After motherboard replacement, check:

• UEFI/Legacy mode
• Secure Boot configuration
• AHCI/RAID configuration
• Intel VMD
• Intel RST
• Storage-controller drivers
• Boot order
• EFI boot entry

If the replacement board exposes the boot disk through a different controller, Windows may fail with 0x7B.

Special Scenario: Virtual Machine INACCESSIBLE_BOOT_DEVICE

The same concept applies to virtual machines.

The error can occur if a VM disk is moved from one controller type to another, such as:

SATA → SCSI

or when the VM configuration changes and Windows does not have the required boot-critical controller driver.

Restore the original virtual storage-controller configuration or ensure Windows has the appropriate driver before migrating the boot disk.

What Not to Do

Avoid random troubleshooting that can make recovery more difficult.

Do not:

• Format the SSD immediately
• Delete partitions without understanding them
• Randomly change AHCI/RAID/VMD settings
• Initialize a disk containing required data
• Delete the EFI partition
• Run commands against an unidentified partition
• Reinstall Windows before checking the disk
• Assume every 0x7B error means SSD failure
• Keep forcing a visibly failing HDD through intensive scans without first considering data recovery

Recommended Troubleshooting Order for IT Engineers

A practical sequence is:

1. Ask what changed immediately before the failure

↓

2. Confirm SSD/HDD detection in BIOS

↓

3. Check AHCI/RAID/RST/VMD settings

↓

4. Check UEFI boot configuration

↓

5. Remove unnecessary storage devices

↓

6. Enter WinRE

↓

7. Run Startup Repair

↓

8. Try Safe Mode

↓

9. Roll back recent update/change if applicable

↓

10. Identify the correct Windows partition

↓

11. Check disk/file-system condition

↓

12. Inspect storage drivers

↓

13. Check BCD/EFI configuration

↓

14. Rebuild boot files where appropriate

↓

15. Test SSD/HDD health

↓

16. Back up/recover data if hardware failure is suspected

↓

17. Consider Windows repair/reinstallation only after appropriate diagnostics

This order reduces the risk of destroying a perfectly recoverable Windows installation.

Can INACCESSIBLE_BOOT_DEVICE Cause Data Loss?

The BSOD itself does not necessarily delete files.

However, the underlying cause may involve:

• Failing SSD
• Failing HDD
• File-system corruption
• Partition corruption
• Storage-controller failure

Therefore, if important data is stored on the computer and the disk shows signs of hardware failure, data recovery should take priority over repeated repair attempts.

Can Antivirus Cause INACCESSIBLE_BOOT_DEVICE?

It is possible for low-level software interacting with storage to contribute to boot failures, particularly software using file-system or storage filter drivers.

Microsoft's startup troubleshooting guidance for STOP 0x7B includes checking non-Microsoft upper and lower filter drivers when investigating certain cases.

However, do not assume antivirus is responsible without evidence.

Does INACCESSIBLE_BOOT_DEVICE Mean the SSD Is Dead?

No.

The error means Windows cannot access the required boot device correctly during startup.

The SSD may be completely healthy while the real problem is:

• Wrong SATA mode
• Wrong VMD setting
• Missing storage driver
• Damaged Windows update
• Corrupted boot configuration
• EFI problem
• Storage-controller configuration change

Hardware failure is only one possible cause.

When Should You Reinstall Windows?

Reinstallation should normally be considered after reasonable recovery options have been exhausted, particularly when:

• The storage hardware tests healthy
• Correct BIOS/storage configuration has been confirmed
• Startup Repair fails
• System Restore is unavailable or unsuccessful
• Updates cannot be rolled back
• Boot configuration repair fails
• Windows system files are severely damaged

Before reinstalling, back up important user data whenever possible.

Prevention Tips

To reduce the chance of future boot-device failures:

• Do not change SATA/AHCI/RAID/VMD settings unnecessarily.
• Record important BIOS settings before firmware updates.
• Keep regular backups.
• Maintain adequate free disk space.
• Monitor SSD/HDD health.
• Use reliable power protection on critical systems.
• Create recovery media.
• Keep BitLocker recovery keys securely backed up.
• Verify cloning procedures before replacing the original disk.
• Keep manufacturer storage/chipset drivers available for business-critical systems.

Frequently Asked Questions (FAQ)

Q1. What does INACCESSIBLE_BOOT_DEVICE mean?

It means Windows lost access to the storage device or system partition required to continue booting.

Q2. What is the error code for INACCESSIBLE_BOOT_DEVICE?

The classic Windows bug check is 0x0000007B (0x7B).

Q3. Can a Windows Update cause this error?

Yes. Storage-driver, system or update-related problems can result in boot failure. If the issue began immediately after an update, WinRE provides options for uninstalling recent updates.

Q4. Can changing BIOS settings cause INACCESSIBLE_BOOT_DEVICE?

Yes. Changing storage-controller configuration such as AHCI/RAID can make the Windows boot volume inaccessible.

Q5. My SSD appears in BIOS but Windows gives INACCESSIBLE_BOOT_DEVICE. Is the SSD faulty?

Not necessarily. Detection in BIOS confirms that the firmware can see the device, but Windows may still have a controller-driver, configuration, boot or file-system problem.

Q6. Can switching RAID to AHCI cause the error?

Yes. If Windows was configured to boot using a different storage-controller configuration, changing the mode can result in a boot failure.

Q7. Can changing AHCI to RAID cause it?

Yes. The same principle applies in the opposite direction.

Q8. Can Intel VMD cause boot problems?

Changing VMD configuration can change how the operating system accesses NVMe storage. If Windows lacks the required boot-critical configuration or driver, startup may fail.

Q9. Should I disable VMD to fix INACCESSIBLE_BOOT_DEVICE?

Not automatically. Determine the configuration used when Windows was installed before changing VMD.

Q10. Can cloning Windows cause INACCESSIBLE_BOOT_DEVICE?

Yes. It is particularly possible when migrating between different storage-controller technologies or when required boot/system partitions are not cloned correctly.

Q11. Can I fix INACCESSIBLE_BOOT_DEVICE without reinstalling Windows?

Often, yes. Correcting BIOS settings, using Safe Mode, Startup Repair, removing an update, restoring the system or repairing the boot configuration may solve the problem.

Q12. Does Startup Repair fix this error?

It can fix certain startup problems, although it will not repair every storage-controller or hardware failure. Microsoft states that Startup Repair can address several startup issues including damaged system files and boot configuration problems.

Q13. Does CHKDSK fix INACCESSIBLE_BOOT_DEVICE?

CHKDSK may help when file-system corruption is involved, but it will not fix incorrect BIOS storage mode, missing controller drivers or all hardware failures.

Q14. Can Safe Mode fix 0x7B?

Safe Mode is particularly useful for some storage-driver configuration problems. Microsoft documents a scenario in which Safe Mode restores driver Start Type settings following boot-critical hardware changes.

Q15. What if the SSD isn't visible in BIOS?

Investigate the hardware first: SSD seating, cables, power, ports, controller and drive condition.

Q16. Can a bad SATA cable cause this error?

Yes. An unreliable SATA connection can interrupt communication with the Windows boot disk.

Q17. Can a failing NVMe SSD cause INACCESSIBLE_BOOT_DEVICE?

Yes. Storage hardware failure is one of the possible causes of bug check 0x7B.

Q18. Can BIOS updates cause this BSOD?

Yes, particularly if the update resets storage-controller settings or other boot configuration.

Q19. Why does Windows keep entering Automatic Repair?

Windows detects repeated startup failures and may enter the Windows Recovery Environment so recovery tools can be used.

Q20. Should I reinstall Windows immediately?

Usually not. First check the drive, BIOS storage configuration, recovery options, updates, drivers and boot environment. Reinstallation should generally be a later recovery option.

Conclusion

INACCESSIBLE_BOOT_DEVICE (0x0000007B) is a Windows startup BSOD indicating that Windows cannot access the system partition required to continue booting.

The most important diagnostic question is:

What changed immediately before the error appeared?

If the problem started after a BIOS update, check AHCI/RAID/RST/VMD configuration first.

If it started after Windows Update, investigate Safe Mode, Startup Repair, System Restore and update rollback.

If it started after cloning or replacing a disk, check UEFI boot files, EFI System Partition, storage-controller configuration and drivers.

If the SSD/HDD disappears from BIOS or reports hardware errors, investigate storage hardware failure and data recovery before repeatedly attempting Windows repairs.

Microsoft's documentation confirms that STOP 0x7B can result from boot-device failure, storage-driver initialization problems, BIOS/configuration changes, disk-controller changes and storage hardware failure.

For Microsoft's technical references, see Microsoft Learn – Bug Check 0x7B INACCESSIBLE_BOOT_DEVICE and Microsoft Support – Startup Repair.

#tags

#INACCESSIBLE_BOOT_DEVICE #InaccessibleBootDevice #Windows11 #Windows10 #WindowsBSOD #BSOD #BlueScreen #StopCode #0x0000007B #0x7B #WindowsBootError #WindowsBootFailure #WindowsStartup #WindowsRepair #WindowsTroubleshooting #WindowsRecovery #WinRE #StartupRepair #SafeMode #WindowsUpdate #WindowsUpdateError #SSD #NVMe #HardDrive #HDD #SSDRepair #NVMeSSD #BootDevice #BootDrive #StorageDriver #StorageController #AHCI #RAID #IntelRST #IntelVMD #BIOS #UEFI #WindowsBootManager #BCD #BCDRepair #BCDBoot #EFIPartition #BootRepair #DiskRepair #CHKDSK #SystemRestore #WindowsRecoveryEnvironment #ITSupport #ComputerRepair #WindowsTechnicalSupport