Inaccessible Boot Device

Understanding the “Inaccessible Boot Device” Error

The “Inaccessible Boot Device” error appears as a blue screen (BSOD) with stop code 0x0000007B.
It means Windows cannot read the system volume during startup.

This error usually does not mean the drive has instantly failed completely.
Often, the problem is missing storage drivers, a damaged file system, or changes in disk configuration.

Typical Symptoms and Risk Assessment

When this error occurs, the system shows a BSOD before Windows loads.
You may see messages like “Your PC ran into a problem” with “INACCESSIBLE_BOOT_DEVICE.”

Common symptoms include:

• Reboot loop as soon as Windows tries to start

• BSOD after a driver, firmware, or Windows update

• BSOD after cloning a system disk or changing SATA mode in BIOS

In many cases, user data is still present on the disk.
The main risk is overwriting or further damaging the file system during repair attempts.

How Windows Accesses the Boot Device (Technical Overview)

During startup, the firmware (BIOS or UEFI) initializes hardware and hands control to the boot loader.
On Windows, the process typically involves the following layers:

1. Firmware identifies the boot disk (based on boot order or EFI entries).

2. The firmware loads the Windows Boot Manager from the EFI System Partition or MBR boot code.

3. Windows Boot Manager reads the Boot Configuration Data (BCD) to locate the system volume.

4. The kernel loads storage drivers required for the disk controller and file system.

5. The system volume (NTFS on MBR or GPT) is mounted and Windows starts services.

If any part of this chain fails — for example, missing storage drivers or corrupted NTFS metadata — Windows cannot mount the boot volume and raises 0x7B.

Common Root Causes

Several technical issues can trigger “Inaccessible Boot Device”:

• Storage controller mode changed (IDE to AHCI or RAID) in BIOS

• Outdated or missing disk controller drivers after a major update

• Corrupted Boot Configuration Data (BCD) or partition table (MBR or GPT)

• Damaged NTFS file system or RAW partition state

• Disk cloning to a new SSD with different alignment or controller

• Physical disk problems such as bad sectors or failing hardware

Understanding which category applies is essential before choosing a repair or recuperación de datos strategy. 

Initial Recovery Actions Before Deep Repair

Before running advanced tools, it is important to stabilize the situation:

1. Stop forced restarts. If the system loops, power it off cleanly using the power button.

2. Check connections. For desktop systems, verify all SATA or NVMe cables and power connectors.

3. Revert BIOS changes. If you recently changed SATA mode or boot order, restore the previous values.

4. Disconnect extra drives. Leave only the system drive connected to simplify detection.

If the error started after a Windows update or driver installation, rolling back or using System Restore from recovery options can sometimes resolve it with minimal risk.

Advanced Repair Techniques for Experienced Users

Advanced users or technicians may attempt direct repair of the boot path and file system.
These methods carry risk, so they are typically performed after critical data is backed up or recovered.

Using Windows Recovery Environment (WinRE)

Boot from a Windows installation USB or recovery drive and choose Repare su ordenador.
Then use the following options:

• Startup Repair: Automatically attempts to fix boot loader and BCD problems.

• System Restore: Restores registry and drivers to an earlier, known-good state.

Command-Line Repair of Boot Records

From Símbolo del sistema in WinRE:

• Repair the boot records on BIOS/MBR systems:

  • bootrec /fixmbr

  • bootrec /fixboot

  • bootrec /rebuildbcd

• Rebuild boot files on UEFI/GPT systems:

  • bcdboot C:\Windows /l en-us

These commands repair the links between firmware, BCD, and the system partition.

Checking File System Integrity

Run chkdsk on the system volume:

• chkdsk C: /f /r

This scans for logical errors and attempts to reallocate bad sectors.
On heavily damaged disks, this can stress the drive, so recuperación de datos should be considered first.

Offline Registry and Driver Correction

Some specialists edit the offline registry to enable generic storage drivers or disable faulty ones.
Herramientas como WinHex or advanced registry editors can modify the SYSTEM hive.
This is powerful but risky and is best left to professionals familiar with Windows internals.

Safe Data Recovery When Windows Will Not Boot

When boot errors persist, separating “system repair” from “data recovery” is critical.
Windows can be reinstalled at any time, but overwritten user data is often unrecoverable.

The safest order is:

1. Identify signs of hardware failure (unusual noises, SMART errors, repeated I/O timeouts).

2. If the drive is failing, consider creating a sector-by-sector image first.

3. Use read-only software de recuperación de datos to scan the disk or its image.

4. Copy important files to a different healthy disk.

A dedicated herramienta de recuperación de datos como Amagicsoft Data Recovery scans at the file system and raw data level.
It rebuilds folder structures and recovers files even when the partition looks RAW or is not bootable.

Recovering Files with Amagicsoft Data Recovery (Step-by-Step)

The following workflow shows how to recover data from a system that shows “Inaccessible Boot Device.”
You will need a second working Windows machine and an external drive.

Step 1: Remove and Attach the Problem Drive

1. Power off the affected PC and unplug it.

2. Remove the system disk carefully (follow hardware safety guidelines).

3. Connect the disk to a working PC using a SATA port, NVMe slot, or USB adapter.

4. Ensure Windows detects the drive, even if it appears as RAW or unallocated.

Step 2: Install and Launch Amagicsoft Data Recovery

1. On the working PC, download and install Amagicsoft Data Recovery on a healthy internal or external drive.

2. Inicio Amagicsoft Data Recovery and wait for it to list all connected disks.

Step 3: Select the Source Disk

1. Select the non-bootable system disk as the scan target.

2. Choose a Full Scan o Exploración profunda mode for maximum recovery on damaged file systems.

3. Start the scan and allow it to complete without interrupting the process.

Step 4: Preview and Filter Recoverable Files

1. Use file type filters (documents, photos, videos) to narrow results.

2. Abra el Vista previa panel to verify file integrity where available.

3. Mark critical folders such as Users\YourName\Documents, Escritorio, y Pictures for recovery.

Step 5: Save Data to a Safe Location

1. Choose a different physical drive as the destination for recovered data.

2. Start the recovery process and confirm that important files open correctly.

3. Only after confirming backups should you attempt reinstalling or reformatting the original system disk.

Amagicsoft Data Recovery operates in read-only mode on the source disk, which helps protect remaining data during scanning and export.