INACCESSIBLE_BOOT_DEVICE error in Windows: causes and solutions

You're peacefully using your Windows computer when, suddenly, you turn on the PC and a blue screen appears with an error message. INACCESSIBLE_BOOT_DEVICEThe system won't start, it keeps restarting, and to top it all off, it won't let you access your desktop. It's one of those errors that strikes without warning and, if you don't know what to do, it's quite alarming.

The good news is that, although the error is alarming, in most cases it can be fixed without having to format your computer or lose your data. This error usually indicates that Windows has stopped being able to access the boot partition or device correctlyThis is usually due to a faulty driver, a botched Windows update, a changed BIOS/UEFI setting, or even a disk problem. Let's take a look, step by step, at all the common causes and possible solutions.

What does the INACCESSIBLE_BOOT_DEVICE error mean?

The INACCESSIBLE_BOOT_DEVICE error message appears in a blue screen of death (BSOD) It indicates that, during the boot process, Windows cannot continue reading from the drive where the operating system is installed. In other words, the system starts, begins loading, and at some point loses access to the system partition (the drive where Windows is located), so it stops to prevent damage or data loss.

In technical terms, this error corresponds to the stop code. 0x7BIt can appear right after installing a major Windows update, when switching from a hard drive to an SSD, after modifying the SATA settings in the BIOS/UEFI, after a sudden power outage, or even when moving the drive to another computer with different hardware.

In addition to the INACCESSIBLE_BOOT_DEVICE error message itself, other typical Windows startup errors are sometimes associated with it, such as “BOOTMGR is missing”, “NTLDR is missing”, “No bootable device – insert boot disk and press any key” or messages indicating that some critical system file is missing (such as a certain .sys o . DllThey all point to a problem in the MBR/BCD or in the boot partition.

Most common causes of the INACCESSIBLE_BOOT_DEVICE error

This blue screen can originate from many sources, so It is important to understand the most typical causes well. Before we start messing around with things haphazardly. Some of the most frequent reasons are:

• Damaged, missing, or incompatible storage controllers (drivers), including third-party filter drivers that "hook" onto the storage stack.
• Damage to the file system or boot partitionFor example, after an unexpected shutdown, bad sectors, or logical errors on the disk.
• BIOS/UEFI Changes, such as modifying the SATA controller mode (IDE, AHCI, RAID) or disabling/enabling certain storage options without Windows having the appropriate driver.
• Using a different storage controller than the one used during Windows installationThis is typical when cloning a disk or migrating from one controller to another.
• Moving the disc to another team with a different motherboard or storage controller, where the loaded drivers do not match the new hardware.
• Physical hardware problems: damaged hard drive/SSD, motherboard with damaged controller, faulty SATA cable, damaged NVMe slot, etc.
• Faulty or incomplete Windows updates, including TrustedInstaller failures or component store (WinSxS) corruption that leaves packages in an “Install pending” or “Uninstall pending” state.
• Corrupted or missing boot files in the System partition (the one that usually appears as “SYSTEM” when using diskpart > list vol).
• Abnormal entries in the GPT partition tableFor example, a blank GPT entry before the boot partition.
• Malicious software that modifies system files, drivers, or boot entries, causing Windows to fail to start correctly.

In many modern devices, especially with SSD and automatic updates enabledThe error appears after a Windows update night, a scheduled restart, or after installing a large system patch. The typical pattern is: the PC was working fine, it restarts to update, and on the next boot, the blue screen appears with INACCESSIBLE_BOOT_DEVICE.

First steps: Entering the Windows Recovery Environment (WinRE)

Before applying most solutions you will need access to the Windows Recovery Environment (WinRE) or boot from a Windows 10/11 installation media (USB or DVD). From there you can use advanced options, run commands, repair startup, etc.

If the computer no longer boots into Windows, the normal thing is that WinRE only appears after several consecutive boot failuresYou can force this situation by turning on your PC and then force-shutting it down (by holding down the power button) as soon as Windows starts loading, repeating this process about three times. On the third or fourth attempt, the Recovery screen should appear.

If WinRE doesn't appear automatically, you can resort to a Windows installation USB or DVD of the same version you have installed. Boot from that media (configuring the boot order in the BIOS/UEFI) and, on the first installation screen, instead of installing, press on “Repair the equipment” bottom left. You'll also reach the recovery options.

Check disk and file system status

A fairly common cause of the error is that the disk has bad sectors or logical corruption in the file system, especially on the partition where Windows is installed. Before you go crazy with configurations, it's a good idea to verify that the storage is healthy.

If you manage to boot from another system or from an environment that allows you to run applications, you can use tools such as CrystalDiskInfo To view the SMART status of the drive. If the program indicates that the drive is in a "Bad" or "Caution" state, the wisest course of action is back up and replace the disk as soon as possible.

If the disk looks fine but you suspect file system errors, you can use chkdsk from the WinRE command prompt:

1. From WinRE, enter Troubleshoot > Advanced Options > Command Prompt.
2. Identify the drive letter where Windows is installed. In the recovery environment, it's not always C:; sometimes it's D: or another drive. You can use diskpart, then list voland locate the partition by size and label.
3. Once identified, execute the command chkdsk X: /f /r (replacing X: with the correct letter).
4. Let the process finish; it may take a while if the disk is large, since scans bad sectors and repairs logical errors.

After completing chkdsk, try restarting. If the problem stemmed from file system corruption, the computer will often... will restart normally.

Start in Safe Mode

El Windows Safe Mode It's a minimal environment where only essential services and drivers are loaded. Often, simply booting into this mode allows Windows to perform internal adjustments and Fixes startup problems related to controllers.

To enter Safe Mode from a Windows system that is still booting, you can go to Settings > Update & security > RecoveryIn the Advanced Startup section, choose “Restart now” and, after the restart, follow the route Troubleshoot > Advanced options > Startup settingsWhen you restart, you'll see a list of options where you can choose. “Enable Safe Mode” (usually by pressing the 4 key). If you prefer, you can also use the tool to modify the boot configuration with msconfig and force a safe mode boot.

If you can't get into Windows, first navigate to WinRE (as we saw earlier) and follow the same menu path to Startup Settings. Once in Safe Mode, if the system manages to boot, simply... Restart normally then. In many cases, this resolves the conflict that caused the INACCESSIBLE_BOOT_DEVICE error.

Update and review storage drivers

The controllers that manage disk access (SATA, AHCI, NVMe, RAID controllers, etc.) are critical. corrupt, outdated, or incompatible driver It can break the boot process on the first restart after an update.

If you manage to get into Windows (even in Safe Mode), open the Device administrator (right-click on the Start button > Device Manager) and especially check the section “IDE ATA/ATAPI controllers” or the storage sections.

An element usually appears called something like “Standard SATA AHCI Controller” or the chipset/motherboard's own driver. Right-click and select "Update driver"You can let Windows automatically search for or download the drivers from the manufacturer's website (Intel, AMD, motherboard or laptop manufacturer).

If you prefer something more automated, you can also use third-party tools such as Driver Booster or other driver updatersHowever, it's always best to rely on the manufacturer's official drivers. Keeping these drivers up to date not only prevents boot errors, but also improves system performance and stability.

Repair Windows startup automatically

When the problem lies in the boot configuration but isn't immediately obvious, you can resort to the option of “Startup Repair” included in WinRE. This tool analyzes the boot configuration, looks for inconsistencies, and rebuilds the damaged elements if possible.

1. Boot from WinRE (either from the system itself or using an installation USB/DVD).
2. Go to Troubleshoot > Advanced Options > Startup Repair.
3. Select your Windows installation when prompted and let the tool do its work.

This process may take a while, but it is quite safe and in many cases is sufficient to restore the boot process without needing to touch anything elseIf Startup Repair doesn't solve the problem, then more manual solutions will be necessary.

Repair the boot record (MBR/BCD) manually

If the boot configuration files or database (BCD) are corrupted, the system may display the error INACCESSIBLE_BOOT_DEVICE or other boot messages. From the WinRE command prompt you can repair the MBR and bootloader manually.

At the WinRE command prompt, run these commands one by one, pressing Enter after each one:

• bootrec /fixmbr – repairs the master boot record (MBR).
• bootrec /fixboot – generates a new boot sector compatible with Windows.
• bootrec /rebuildbcd – analyzes available Windows installations and rebuilds the BCD store.

When you finish, write exitRestart your computer and check if the system now boots normally. These commands are frequently used to troubleshoot errors such as Bootmgr is missing or problems with the Windows boot menu.

Rebuild boot files with BCDBoot

When the problem is more serious and files like Bootmgr Or if the EFI/BIOS boot structure is severely damaged, you can use the tool BCDBoot to regenerate the boot files from scratch, starting from a Windows installation that does exist on disk.

1. Enter the WinRE command prompt.
2. Usa diskpart > list disk > select disk X > list vol to locate:
   • The partition where Windows is installed (the one with the folder) Windows).
   • The system/boot partition (often around 100-500 MB, sometimes labeled “SYSTEM” or “Reserved”).
3. If the SYSTEM partition does not have a drive letter, assign it one with assign letter=R (for example) after selecting it with select volume.
4. Exit diskpart with exit.
5. Run a command like this (adjusting drive letters):
   bcdboot D:\Windows /s R: /f ALL

That command copies the necessary boot files from the Windows folder (D:\Windows in the example) to the system partition (R:) and Configure the boot process for both BIOS and UEFIAfter this, restart and check if the error has disappeared.

Check and correct BCD entries

If Windows still won't start, the Boot Configuration Database (BCD) may have incorrect inputs or poorly defined routesFrom WinRE, run bcdedit to list the current configuration.

You should pay attention to two key sections:

• Windows Boot Manager ({bootmgr}): here check that the entries device y path They point to the correct partition and file.
  • In UEFI systems, it usually has something like device partition=\Device\HarddiskVolumeX y path \EFI\Microsoft\Boot\bootmgfw.efi.
  • In BIOS systems, normally device partition=C:.
• Windows boot loader ({default}): check out device, osdevice, systemroot y pathwhich should point to the correct Windows partition and path (for example, device partition=C: y systemroot \Windows).

If something is wrong, you can change it with commands like bcdedit /set {default} device partition=C:Before you start modifying a lot of things, it's a good idea export a backup from the BCD with bcdedit /export C:\temp\bcdbackup and, if something goes wrong, restore it later with bcdedit /import C:\temp\bcdbackup.

Enable AHCI mode in the BIOS/UEFI

Many users have found that, when activate AHCI mode For SATA ports in the BIOS/UEFI, the error disappears instantly. AHCI is the recommended mode for modern SSDs and hard drives, compared to IDE or legacy modes.

The procedure It varies depending on the motherboard.But normally you have to:

1. Turn off the computer completely.
2. Turn on and repeatedly press the key to enter BIOS/UEFI (usually Del, F2, F10 or F12(depends on the manufacturer).
3. Look in the advanced menus for the section on Storage, SATA configuration or similar.
4. Change the controller mode to AHCI whether it was in IDE or another unsupported mode.
5. Save changes and exit.

It's important that this change is consistent with how Windows was installed. If the system was originally installed in IDE mode and you switch to AHCI without Windows having the driver enabled, it can also cause problems. In many cases, however, Switching to AHCI fixes the storage controller conflict that was causing the blue screen.

Uninstall the latest Windows update

The major Windows 10 or 11 updates These are one of the most common causes of this error. Sometimes a package is installed that includes an incompatible driver or that corrupts parts of the system.

If you suspect the problem started right after updating, a good strategy is uninstall the last installed package from the recovery environment.

1. Open WinRE and open the Symbol of the system.
2. Check which drive Windows is installed on (for example C: or D:).
3. Run Dism /Image:C:\ /Get-Packages (replacing C: with the correct letter) to list all packages and their date.
4. Locate the most recent package (by installation date) that appears to be the latest quality or cumulative update.
5. Uninstall it with a command like this: Dism.exe /Image:C:\ /remove-package /PackageName:NombreDelPaquete, using the exact name shown in the listing.

After removing that package, restart your computer. If the error was due to that update, the normal solution is that Windows will restart normally.Later you can decide whether to temporarily block that update or wait for Microsoft to release a fix.

Remove packages in "pending" state

Sometimes, Windows leaves updates in a state “Installation pending” o “Uninstall pending”This blocks the update process and can cause boot failures, including the INACCESSIBLE_BOOT_DEVICE error. In these cases, those packages need to be removed from the queue.

From the WinRE command prompt, you can follow these steps advanced steps:

1. Temporarily load the Software Registry branch with:
   reg load HKLM\temp C:\Windows\System32\config\software
2. Delete certain entries related to pending sessions:
   reg delete "HKLM\temp\Microsoft\Windows\CurrentVersion\Component Based Servicing\SessionsPending" /v Exclusive
3. Download the branch with:
   reg unload HKLM\temp
4. Relist packages:
   • Dism.exe /image:C:\ /get-packages to identify those with a "Install pending" status.
5. Create a temporary folder and move the conflicting packages:
   mkdir C:\Temp\packages
Dism.exe /image:C:\ /remove-package /packagename:NombreDelPaquete /scratchdir:C:\Temp\packages

This procedure is used to break the pending packet lock which prevents the system from finishing configuring the updates and starting up correctly.

Troubleshooting problems after a Windows Update

When error 0x7B appears immediately after an update, in addition to uninstalling packages, it's advisable to roll back any pending actions and clean up the system state. Microsoft recommends:

• Run dism /Image:C:\ /Cleanup-Image /RevertPendingActions to reverse pending update actions.
• Ir a C:\Windows\WinSxS and check if a file exists pending.xmlIf it exists, rename it to pending.xml.old to prevent those pending instructions from being processed.
• Use regedit to load the hive COMPONENT (such as “OfflineComponentHive”) and remove keys such as PendingXmlIdentifier that indicate pending operations.
• Load the hive SYSTEM (such as “OfflineSystemHive”), go to Control/Session Manager and delete the key PendingFileRenameOperations If it exists, after making a backup.

These advanced operations help the system forget status pending corrupt updates and be able to start up without getting stuck in a failed configuration loop.

Review critical services and drivers for startup

Windows startup depends on a number of kernel services and drivers (such as ACPI, DISK, PARTMGR, VOLMGR, VOLUME, VOLSNAPetc.). If any of them are disabled in the Registry or use a problematic third-party driver, you may encounter a 0x7B error.

Using the Registry Editor from WinRE (loading the SYSTEM hive as “OfflineSystemHive”), go to the key HKEY_LOCAL_MACHINE\OfflineSystemHive\Services and verify that the inputs for those critical services exist and that the value Start is the 0 (Start in “Boot” mode).

If keys are missing or corrupted, you can try to restore the SYSTEM hive from the folder RegBack with commands like:

Registry restoration:
cd C:\Windows\System32\config
ren SYSTEM SYSTEM.old
copy C:\Windows\System32\config\RegBack\SYSTEM C:\Windows\System32\config\

With this I know restores a previous version of the registry which can bring back to life a system that wouldn't start due to misconfigured drivers or services.

Remove problematic filter drivers

Some programs, especially security, encryption, or virtual disk software, install “UpperFilters” and “LowerFilters” filter controllers These are inserted between the system and the disk. If these drivers fail, they can disrupt access to the boot device.

From the Offline Registry, within the loaded SYSTEM hive (OfflineSystemHive), you must review routes on the table:

• Control\Class\{4D36E96A-E325-11CE-BFC1-08002BE10318} (disk storage controllers).
• Control\Class\{4D36E967-E325-11CE-BFC1-08002BE10318} (network controllers, sometimes with filters).
• Control\Class\{4D36E97B-E325-11CE-BFC1-08002BE10318} (volume devices).
• Control\Class\{71A27CDD-812A-11D0-BEC7-08002BE2092F} (assembled volumes).

If you find tickets UpperFilters or LowerFilters that do not correspond to standard Windows drivers (for example PartMgr) but to suspicious external software or software that you have already uninstalled, you can delete those values After backing up the key, this prevents the filter from loading at startup and reduces the likelihood of it causing the INACCESSIBLE_BOOT_DEVICE error.

Run SFC and CHKDSK on the installation

If the system still fails to start, another recommended step is to combine the use of chkdsk ’s relationship with the System File Checker (SFC) to repair damaged files.

1. From WinRE, open the command prompt.
2. Run chkdsk X: /f /r on the partition where Windows is located to correct disk errors.
3. Once finished, switch to that drive with X: and run sfc /scannowThis will scan and will replace corrupted system files using the Windows cache.

This process usually takes time, but it is very useful when the failure is due to corrupted system files after sudden shutdowns, power outages, or malware.

Scan the system for malware

Although it's not the most common thing, a virus or malware It could also be the root of the problem, especially if you have modified drivers, boot files, or registry keys related to storage.

Windows 10 and 11 incorporate Microsoft Defenderwhich offers fairly comprehensive protection. Ideally, one should perform a complete and exhaustive analysis of all units, not just a quick test. This type of test can take several hours, but it's worth it to rule out deep infections.

If your PC won't boot, you can use third-party antivirus rescue media or boot from another system and run a antimalware scanner on the affected disk. The goal is to remove any malicious software that may be blocking the boot process or damaging critical components.

Check physical connections, BIOS and hardware

Beyond the software, we must never forget the physical problems. SATA cable poorly connected, NVMe SSD improperly seated in its slot or a faulty motherboard port can perfectly cause an INACCESSIBLE_BOOT_DEVICE error.

It is advisable to turn off the equipment, unplug it from the power outlet and check all disk connectionsCables, power supply, SATA ports, M.2 slots, etc. If you have another PC, testing the drive there also helps to rule out whether the problem is with the drive or the motherboard/controller.

In the BIOS/UEFI, verify that the disk appears in the list of drives and that it is configured as first boot device appropriate. If something seems off, you can load the BIOS/UEFI defaults from the interface itself to rule out a bad configuration.

What to do if nothing works: reinstall Windows and recover data?

If you've tried all reasonable options (repairing the disk, MBR/BCD, uninstalling updates, checking drivers, BIOS, etc.) and the error persists, you may need to consider a complete reinstallation of windowsIt's a more radical measure, but sometimes it's the only way to break the cycle.

Before getting involved, it is essential save important dataIf the disk is still readable but the system won't boot, you can use data recovery solutions that allow you to create a Bootable USBStart the computer from there and copy the files to another external drive.

Professional recovery tools, such as certain suites that offer a recovery mode “Recover from Crash Computer”They allow you to create a bootable drive, boot a minimal Windows environment, and extract documents, photos, and other valuable information even for systems that won't start. The process usually involves:

• Create a bootable USB or DVD from another PC.
• Configure the BIOS to boot from that medium.
• Start the recovery tool and copy data to an external disk.

Once your data is safe, then you can choose to format the drive and install Windows from scratch with an official installation USB drive. The installer itself may retain a folder called windows.old with remnants of the previous system, but it's not advisable to rely solely on that: it's better to go with a backup already made.

As you can see, the INACCESSIBLE_BOOT_DEVICE error can have many causes, from a simple, poorly processed update to a serious hardware failure, but you also have a good range of solutions: checking the disk, using chkdsk and SFC, booting in Safe Mode, repairing the MBR and BCD, uninstalling problematic Windows Update packages, adjusting the BIOS/UEFI, or resorting to advanced repair and recovery tools; by following these options calmly and systematically, in most cases you will be able to resolve the issue. Restore your Windows startup without losing your data or going crazy. Share this information and more people will know how to solve the INACCESSIBLE_BOOT_DEVICE Error in Windows.