▶ INACCESSIBLE_BOOT_DEVICE BSOD error
▶ When does Inaccessible Boot Device error occur?
▶ Fix Inaccessible Boot Device BSOD error with different solutions
▶ Summary
INACCESSIBLE_BOOT_DEVICE BSOD error
“Hello. I’d like to say this is a little bit strange because I get the error just in
the process of working. The screen stills for nearly one second and gives following
interface reading ‘Your PC ran into a problem and needs to restart. We’re just
collecting some error info, and then we’ll restart for you. (0% complete)’. There is
a line beneath with a smaller font size saying ‘if you’d like to know more, you can
search online later for this error: INACCESSIBLE_BOOT_DEVICE.’ So, what’s wrong? Why
would my boot device becomes inaccessible?”

Search online, you may find there are many users are in the same trouble. Some of
them encounter inaccessible boot device on Lenovo ThinkPad laptop, some of them on
HP Pavilion, and some on ASUS, SONY VAIO, Toshiba, and so on. The background OS also
varies from Windows XP to Windows 10, and mostly on Windows 10. What does the
INACCESSIBLE_BOOT_DEVICE error mean and when would it happen?
When does Inaccessible Boot Device error occur?
INACCESSIBLE_BOOT_DEVICE usually comes with Blue Screen of Death (BSOD) error in
Windows, with the declaration that the PC cannot boot normally. According to users’
feedback, this error happens mostly in following situations.
Inaccessible boot device after Windows Update. The error is likely to emerge after you installing Windows latest updates in a period of time.
Inaccessible boot device after installing Windows 10 on SSD. No matter you clean install Windows 10 on SSD or migrate Windows 10 to SSD, the error means there is something wrong about the system files on the boot SSD. You may have missed something during installation or cloning.
Inaccessible boot device after system partition resized. Likewise,
inappropriate operations may damage system files and lead to this type of
errors. If you’d like to resize system drive, please refer to how to partition C drive properly.
Inaccessible boot device after BIOS update.
Except for covering situations, the error also happens on a damaged hard disk, i.e. a
disk with many bad sectors on. In some cases, the error displays for seconds and
then the PC restarts automatically. However, the error occurs once again on the
restart. It is also called boot device restart loop. Then, what should you do to get
this type of inaccessible boot device fixed?
Fix Inaccessible Boot Device BSOD error with different solutions
To fix the problem that caused by different factors, you need to take measurements
accordingly. If it is caused by BIOS update, you can revert to previous BIOS
settings. If it is caused by Windows 10 installation, perform a clean install or
Windows cloning once again. If it is caused by other elements like Windows
Update or bad sectors, check these methods out to see if they are helpful.
Fix Inaccessible Boot Device with Installation Disc
If you have a Windows installation disc or repair disc, you can tell Windows back to
a state when it works fine.
Insert the disc to your Lenovo PC or any PC has the error and then boot off.
You may need to change boot order in BIOS if it falls back to the internal
disk.
At the installation interface, choose language, time and keyboard input and
click Next.
Click on Repair your computer in the lower-left corner.
Click on System Restore in Advanced Tools. Then, let it
recover Windows to a previous System Restore point.
After successful boot up, type services.msc in Run to open Services.
Find Windows Update, right click it and choose Stop to prevent
Windows from updating, so that you can avoid such error in the future.
Most Windows PCs create system restore points by default. To fix ASUS laptop
inaccessible boot device error or the like, it could be the easiest way. If the
error still cannot be solved due to unknown causes, you may want to try fixing the
problem by restoring Registry Backup.
Fix Inaccessible Boot Device via Registry Backup
It is little-known that the operating system keeps a backup of a working Registry for
recovery purposes. If you don’t have a system backup around, you can manually
restore Windows to a working state.
Start your computer with Advanced startup options, and then
go Troubleshoot > Advanced options > Command Prompt. The command prompt
should start on X: \Windows \System32 if you run it as administrator.
Type D: \ (Windows will be moved to another partition with a
different drive letter in this mode, usually D drive. but you can typedir to verify if you’re in the correct drive. If you are, you should
see the contents of Windows OS).

Type cd D: \Windows \System32\ (enter into the System32 folder).
Type mkdir configBak (create a folder to temporary backup of files
on the config folder).
Type copy config configBak (create a temporary backup of the files
in the config folder).
Type cd config\RegBack (move inside the RegBack).
Type dir (verify the content of the RegBack folder, the size of
those files should be similar to the ones in this picture. If any of the files
shows 0, there is no backup available. In other words, you cannot repair
inaccessible boot device in this way.).

Type Copy * ..\* (copy the files from the RegBack folder to the
config folder). Close the Command Prompt to complete the task and restart your
PC.
Tips: if the Windows on your PC is not on D drive in that mode, you
need to replace D with the correct drive letter in all related steps.
Repair Corrupted System Files by Rebuilding MBR
If aforementioned solutions still don’t work in your case, or you don’t want to
restore to previous state in the event of corrupted system files, you can repair the
error by rebuilding a MBR.
AOMEI Partition Assistant Standard is a free partition manager that can assist you fix inaccessible boot device on HP PC or the
like in Windows 10/8/7/XP/Vista by rebuilding the corrupted MBR. Free download to have a try.
Preparations:
1. Connect the media to the fine PC. Install and run AOMEI Partition Assistant on that computer, too.
2. At main interface, click on Make Bootable Media in the left
Wizards. Then, follow the wizard to complete.

3. Insert the bootable media to your PC that has inaccessible boot device error and
start off. You’ll see AOMEI Partition Assistant again once login.
4. Right click the disk you want to repair and click on Rebuild MBR from the menu.

5. In the pop-up window, choose the proper MBR type for your Windows.

6. Click Apply and then Proceed to commit the task.
Finally, restart your computer.
Tips: AOMEI Partition Assistant Standard also supports check errors
for hard drive and partitions. Surface Test and Check
Partition features are available in the event of bad sectors. For
detailed information, please refer to check hard drive for errors in Windows 10.
Summary
When your PC encounters INACCESSIBLE_BOOT_DEVICE BSOD error in Windows 10/8/7, you
can solve the problem by restoring system points, restoring registry backup, or
fixing corrupted MBR with the help of different tools.
AOMEI Partition Assistant Professional, the advanced version of Standard, provides
more powerful features. For example, you can transfer OS to GPT SSD disk without reinstalling if the current disk is about to fail.