As its name indicates, the INACCESSIBLE BOOT DEVICE BSOD reflects some kind of issue with a Windows installation’s designated boot device. When this error occurs, it means that the Windows file system tried to read the boot device and failed. Most often, this means the boot device failed to initialize.
Alternatively, when the boot loader attempted to access the designated boot device, it did not recognize its data as a file system structure. In simpler terms, the boot process did not find a bootable system where the boot configuration data said it was supposed to be. At the highest possible level, this error indicates no boot device is known or accessible to the problem PC.
Common Causes of INACCESSIBLE BOOT DEVICE BSODs
Most of the time, the INACCESSIBLE BOOT DEVICE error occurs because a boot device has failed or is unreadable. During input/output (I/O) initialization the boot device driver might not have been able to initialize the boot device (which is a hard drive or SSD, perhaps even one of the best SSDs). Other potential causes include:
- File system initialization could not recognize the data on the boot device.
- Device parameters for the boot device have become damaged, corrupted, or are invalid.
- If an error occurred during initial system installation, the OS may have been installed on an unsupported disk controller, or a valid driver for a non-standard disk controller may not be valid or available.
By far the most common situations when this error occurs, involve changes to the Windows boot environment of some kind. Repartitioning the boot/system drive, alterations to the boot configuration data (BDC), BIOS configuration changes, or installing a new or different disk controller can provoke this stop code, which takes numeric value 0X0000007B (aka 0X7B). This error code is discussed in more detail in the Microsoft Docs page for INACCESSIBLE_BOOT_DEVICE.
Recovering From INACCESSIBLE BOOT DEVICE Errors
Sometimes, this error will occur as a one-time glitch. If that happens, some kind of transitory error interfered with one boot-up, but Windows recovers on the next restart. If that happens on one of your PCs, be sure to make an image backup with some means to recover from bootable media if the problem recurs. I use Macrium Reflect Free to make daily image backups; that program’s bootable Rescue Media on a USB Flash drive offers an alternate boot, and can restore the most recent image backup to my boot/system disk any time it’s needed.
In fact, that bootable Rescue Media also includes a “Fix Windows Boot Problems” option that I have used many times to repair boot issues. It’s adept at fixing boot errors that may pop up when editing or altering boot menus or boot configuration data. Access to this facility is depicted in the following screenshot, and fully described in a useful Macrium Knowledge Base article (50168).
Microsoft’s repair advice for INACCESSIBLE BOOT DEVICE also includes the following recommendations:
- Revert recent hardware changes: If you’ve recently added or changed system hardware – especially disk drives or related drivers or drive controllers – remove them from the system. Often this will immediately fix what’s wrong because the boot drive order can be affected in the aftermath of such changes. If this fixes the problem, you’ll need to make configuration changes to resolve potential IRQ or I/O port conflicts to get all parts working.
- Undo BIOS changes: If you’ve reset boot order or drive priority improperly, restoring previous settings will usually set things right. This stop code may pop up, for example, when changing controller mode from legacy to AHCI, or from RAID to AHCI (or vice-versa) in the BIOS. See our article on how to enter your BIOS for help getting into the menu.
- Check storage device compatibility: If you’ve added a new storage device or controller, you must check to make sure it’s compatible with Windows (see Windows 10 Specifications for details). If you’ve added a controller, make sure the driver is compatible with your Windows version. It might be a good idea to try a fresh download from the maker or OEM, just to be sure the driver is not damaged or corrupted.
Bottom Line on INACCESSIBLE BOOT DEVICE Errors
In the vast majority of cases, the INACCESSIBLE BOOT DEVICE error will get resolved when you undo your most recent system changes. In a few cases, though, you may not be able to get Windows to recognize a boot device through any of the preceding fixes. If that happens you have no choice but to perform a fresh, clean install of your specific Windows version (see our article on how to do a repair install of Windows). And if that doesn’t work, your drive could be physically damaged.
You may also have to forgo new drives or controllers if you are unable to make them work, even under such a clean install. In my 30 years’ working with Windows this has never happened to me, but one does read about such things online occasionally. Through trial and error, and working with known, good and compatible hardware components, you should be able to put a working Windows configuration together, even in the face of such problems.