Boot error INACCESSIBLE_BOOT_DEVICE, drive letters C: and D: switched

Question

Issue:

Error (blue screen) when booting with stop code (DE Stillstandcode) INACCESSIBLE_BOOT_DEVICE. Computer restarts automatically and then freezes with message “automatic repair being prepared” (DE “Automatische Reparatur wird vorbereitet”). After manual shut down, the same happens all over again.

System:

Lenovo IdeaPad C340-15IWL with pre-installed Windows 10 (updated to latest version / fixes) with two drives:

128 GB SSD with Windwos and program files (C: “Windows-SDD”)

1 TB HDD as data storage (D: “Data”)

Reason:

Not clear. Just three days before a BIOS update (ALCN28WW V2.05) has been installed, after which the fingerprint scanner didn’t work any longer. Lenovo support suggested to reset BIOS to defaults and re-install driver, which did not solve the problem, but at least the computer still worked. After another restart, the issue occurred.

Troubleshooting:

1)     Loaded default settings in BIOS again à no change.

2)     Booted from Win 10 installation USB flash drive, chose repair options (DE “Computerreparaturoptionen”), then troubleshooting (DE “Problembehandlung”), then start help (DE “Starthilfe”) à PC could not be repaired; then chose advance options (DE “Erweiterte Optionen”), command prompt (DE “Eingabeaufforderung”); change to drive C: and D: and could see that all directories are still there, BUT DRIVE LETTERS ARE SWITCHED: C: shows as “Data” holding all directories formerly under D:, and D: shows as “Windows-SDD” holding all directories formerly under C:

Pretty sure that this switch of drive letters is related to the issue (Windows probably tries to boot from C:, which is the wrong drive now), not idea how this came, and no idea how to switch it back to make Win work again.

Thanks for any helpful suggestion!

Answer 1

Hi,

Thank you for keeping us posted.

If it is a hardware issue, then the manufacturer should be able to assist you with the repairs. I certainly hope that this gets resolved at the earliest for you.

Let us know if you got the help or guidance you needed by clicking on Yes or No.

Regards,

Prakhar Khare

Microsoft Community - Moderator

Answer 2

Hi,

Thanks for giving it another trial.

I already tried changing disk letters via DISKPART, but with INACTIVE / ACTIVE commands instead of ASSIGN (as recommended in another thread). Unfortunately, these did not work for my kind of drives. Also swapping drive letters via REGEDIT did no solve the problem.

I meanwhile sent in the notebook to Lenovo for repair, they suspected potential hardware issue, will see if and how they can fix it ...

Answer 3

Hi,

Thank you for replying with the updated information.

One of the things that we can try is changing the drive letters using diskpart command and see if the PC boots fine.

1.    Create a bootable media and boot the PC using the media.

2.    On the Install Windows screen, select Next > Repair your computer.

3.    On the System Recovery Options screen, select Troubleshoot> Advanced options > Command Prompt.

4.    Now type in the following commands and hit Enter:

diskpart

list volume

select volume #

assign letter=letter

5.    Restart the PC

Note: # is the drive letter that you want to change the name, andletter is the name that you want to convert the drive to.

Regards,

Prakhar Khare

Microsoft Community - Moderator

Answer 4

Hi,

Thanks for the reply. I did as suggested, but it did not solve the problem.

Not sure from which drive I'm supposed to execute the commands and if this matters at all. When entering command prompt mode, I was on drive X: and can change to C: and D:, I executed first on C:, then on D:, with same result:

BOOTREC /FIXMBR -> process completed

BOOTREC /FIXBOOT -> access denied

BOOTREC /scanos -> 0 Windows installations found

BOOTREC /rebuildbcd -> 0 Windows installations found

As indicated in my original post, drive letters C: (was originally the SSD with Windows and program installations) and D: (was originally the HDD holding data) have somehow switched. When I go to C: in command prompt and execute DIR, it shows me all the content that was supposed to be on D: and vice versa.

That means, I can find the Windows directory that was supposed on C: under drive letter D: now, which might be a symptom of the issue, or the root cause.

So might it help to switch back drive letters C: and D:, and how can this be done?

Thanks and regards.

Answer 5

Hi,

Thank you for writing to Microsoft Community Forums.

I understand that you are facing issues while booting your PC as Automatic Repair keeps failing. I will certainly try my best to assist you with the issue.

One of the things that you can try is rebuilding the BCD using Bootrec commands and see if you are able to boot the PC normally.

1. Create a bootable media and boot the PC using the media.
2. On the Install Windows screen, select Next > Repair your computer.
3. On the System Recovery Options screen, select Troubleshoot> Advanced options > Command Prompt.
4. Now type in the commands and hit enter: BOOTREC /FIXMBRBOOTREC /FIXBOOT

BOOTREC /scanos

BOOTREC /rebuildbcd 5. Restart the PC.

Let us know how it goes, if the issue persists, we will certainly assist you further.

Regards,

Prakhar Khare

Microsoft Community – Moderator