INACCESSIBLE_BOOT_DEVICE (0x0000007B): What to do when Windows won't boot

If you have ever encountered the dreaded blue screen error in Windows accompanied by the code INACCESSIBLE_BOOT_DEVICE (0x0000007B)You'll be fully aware of the feeling of helplessness and confusion it can cause. This error, much more common than many people think, usually appears suddenly and makes it clear that your computer can't access the device or partition where the operating system resides. But what does this message really mean? Why does it happen, and, above all, how can you fix it without losing your data or going crazy?

Throughout this article, I'm going to explain, step by step and very clearly, everything you need to know about this very particular error. Not only will I tell you why it occurs and what the most common causes are, but we'll also take an in-depth look at the full range of possible solutions, from the simplest steps to the most advanced techniques, including how to avoid data loss while you repair your system. In addition, you'll learn all the Tricks which are often recommended by both Microsoft experts and data recovery portals. Let's go!

What does the error INACCESSIBLE_BOOT_DEVICE (0x0000007B) mean?

When your PC boots up and cannot find or access the disk where Windows is installed, the system throws this error accompanied by a blue screen of death (BSOD). The message usually indicates that Windows cannot correctly read the system partitionThis can occur both in Windows 7, 8, 10, and 11, and appears right during the startup process. In some cases, the error occurs after an update, a BIOS settings change, a hardware failure, or even after moving the disk to another computer.

Essentially, the operating system has become 'blind', unable to access the files needed to start. That's why your computer keeps restarting over and over again without getting past that fatal blue screen.

Why do I get the INACCESSIBLE_BOOT_DEVICE error?

The causes are varied and can be due to both software and hardware failures. The most common reasons, according to support forums and specialized websites, are:

• Failed or incomplete Windows updates: After installing an update, incompatibilities with drivers may occur. storage.
• Changing the disk operating mode from the BIOS: For example, switching from AHCI to RAID (or vice versa) without reinstalling drivers.
• Corrupt, outdated, or improperly installed storage drivers.
• Faulty physical connections: A loose SATA or IDE cable, a loose drive, or interfering peripherals.
• Sectors of Boot or damaged partition tables.
• Virus attacks or malware that corrupt the boot sector.
• Move the disk to another computer with a different storage controller.
• Failure of the hardware itself: : Hard drive failure, faulty motherboard or even RAM problems.
• Errors in system files or the Boot Configuration Database (BCD).
• Incorrect BIOS/UEFI update or modification.

Basic first steps before getting into the subject

Before you go crazy and start disassembling your computer or formatting your disk, There are a number of simple checks and steps that can fix the problem in a matter of minutes.:

• Disconnect all unnecessary external devices: Leave only the keyboard and mouse connected to a USB device. Remove external hard drives, printers, and any other accessories. Sometimes, a USB device can interfere with booting if it's selected as the priority device in the BIOS.
• Perform a complete shutdown and discharge residual electricity.Turn off your PC, unplug it, remove the battery if it's a laptop (if possible), and press the power button for 20 seconds. Then plug everything back in and try booting up.
• Check the physical connections of the hard drive: If you have basic knowledge, open the tower (or laptop lid) and make sure the SATA/IDE cable is not loose and the drive is receiving power.
• Enter the BIOS and check the boot order.: Make sure the disk containing Windows is the first one listed and that the BIOS recognizes it correctly.

Specific solutions for the INACCESSIBLE_BOOT_DEVICE error

Solution 1: Use the Last Known Good Configuration

Many errors, especially those resulting from a recent bad configuration, can be solved by starting with the option of Last Known Good Configuration. To access this mode:

• Restart your PC and hold down the F8 key as soon as you turn it on, before the Windows logo appears.
• In the Advanced Options menu, select “Last Known Good Configuration (Advanced)” and press Enter.
• If Windows boots without the error, you'll know it was due to a recent configuration or a problematic driver.
• If it doesn't work, continue with the following methods.

Solution 2: Repair from Windows Recovery Environment (WinRE)

If the operating system fails to boot normally, you can often access the Windows recovery environment (Win) automatically after several failed startup attempts (or after forcing a shutdown three times in a row). From there, you'll have access to several very useful tools:

• Startup repair: Allows Windows to attempt to automatically identify and restore damaged boot files.
• Restore system: If you have previous restore points, you can return to a previous stable system state.
• Symbol of the system: This option is key if you want to perform manual checks and repairs, as we will see in the following sections.

To access WinRE, you can:

• Force power off and on three times in a row during boot.
• Boot from a Windows installation pendrive or DVD and choose Repair equipment instead of installing.

Solution 3: Check and repair hard drive errors

The failure may simply be due to bad sectors or corruption in the disk's file system. From the WinRE command prompt, you can run:

• Enter the command chkdsk C: / r (assuming C is the Windows partition). This command scans the drive for bad sectors and repairs them if possible.
• If the disk is operational and the problems were minor, Windows may boot without problems after restarting.

Solution 4: Rebuild the Boot Configuration Database (BCD)

Sometimes the BCD becomes corrupted or its entries disappear. You can check and rebuild the BCD using the following commands from the WinRE command prompt:

• Check the BCD: bcdedit. Check that the entries (identifier, device, path, etc.) are correct.
• If any entries are missing or incorrect, run:
  • bootrec / scanos (looks for Windows installations not linked to the BCD).
  • bootrec / fixmbr (fixes the master boot sector).
  • bootrec / fixboot (repairs the boot sector of the partition).
  • bootrec / RebuildBcd (recreates the boot configuration database).

These commands often resolve many boot-related errors, provided the problem is in the software or configuration and not the hardware.

Solution 5: Check and update SATA/IDE settings in BIOS

An accidental change or BIOS update can alter the drive's operating mode (for example, from AHCI to RAID), causing Windows to not recognize the drive. To fix this:

• Access the BIOS (usually by pressing F2, Del, Esc, or the key indicated by your manufacturer).
• Look for the SATA controller configuration options.
• Changes the operating mode of AHCI a RAID or vice versa (depending on what was there before or what your motherboard indicates).
• Save the changes and reboot.

Trick: If the error appears after an update or reinstallation, the mode may have changed, and Windows doesn't have the correct drivers for it. Change it back to the previous mode if you know what it was.

Solution 6: Remove viruses from the boot sector

Some viruses and malware specialize in infecting the boot sector, blocking access to the operating system. To eradicate them, you can use tools such as:

• Download the version of on another computer Windows Defender Offline and create a bootable USB or DVD.
• Boot the affected computer from that media and allow the antivirus to scan and clean the boot sector before starting Windows.

This step is especially useful if you've noticed suspicious activity or recent infections on your system.

Solution 7: Check and replace the SATA/IDE cable

Although less common, a damaged or poorly connected cable can cause the BIOS to not detect the drive, resulting in this type of error.

• Check that the cable is properly connected at both ends.
• If you can, try a new cable or one that works on another device.

Solution 8: Restore the system from a previous point

If the error occurred after installing problematic software or drivers, and you have restore points, you can use them to return to a previous configuration where everything was working correctly.

• Access the recovery environment and select “System Restore.”
• Choose a point before the date of the problem and follow the restoration instructions.

Solution 9: Uninstall recent updates that cause the crash

Sometimes, a conflicting update can be the source of the error. Uninstalling it may restore the system to normal:

• Starts in safe mode or with command prompt from WinRE.
• Use the command dism /image:C:\ /get-packages to list installed packages.
• Identify those that were installed just before the failure.
• Eliminate them with dism /image:C:\ /remove-package /packagename:whatever.

You can complete this process by checking for pending installation or uninstallation files (pending.xml) and changing their names to prevent them from running on the next startup.

Solution 10: Pre-repair data recovery

If you suspect that the disk is truly damaged and you have important information on it, the first step should be to try to recover the data before continuing to repair it yourself:

• Use specialized software like MiniTool Power Data Recovery or Wondershare Recoverit, which allow you to create a WinPE bootable USB to recover files even if Windows won't load.
• Connect the bootable USB, boot your PC from it, and follow the recovery wizard's instructions to save critical files to an external drive.

In extreme cases, if the problem is purely physical (strange noises, the drive won't spin, etc.), consult a professional data recovery service, as operating the drive could result in irreversible data loss.

Related errors and how to identify them

The INACCESSIBLE_BOOT_DEVICE error is often accompanied by other blue screen codes related to storage devices or boot corruption. Some of these include:

• UNMOUNTABLE_BOOT_VOLUME (0x000000ED): The boot volume cannot be mounted, usually due to severe file system corruption.
• BAD_SYSTEM_CONFIG_INFO (0x00000074): This is usually related to registry configuration issues or corrupted system files after an update.
• SYSTEM_THREAD_EXCEPTION_NOT_HANDLED (0x0000007E): A faulty driver (often storage related) cannot handle an exception.

The key to identifying what's going wrong lies in writing down the exact error code, trying to remember what changes occurred before the error (new peripherals, updates, driver installations, etc.), and acting accordingly with the solutions we've seen above.