How I fixed the “Reboot and Select proper Boot device…” error

You may have received the dreaded “Reboot and Select proper Boot device or Insert Boot Media in selected Boot device and press a key” error message after switching on your computer. This message means that the computer fails to startup Windows using its boot device. A simple explanation could be that you selected the wrong boot device in the computer UEFI setup (or BIOS). The solution in that case is to restart the computer, to enter the UEFI (or BIOS) configuration and to select the proper boot device.

But this message could also mean that the system partition has been corrupted and needs to be repaired. We will see in this tutorial how I did it with a few simple command lines.

Reboot and Select proper Boot device
Reboot and Select proper Boot device

There are many different situations that could have led to this error message: a wrong boot device in the UEFI setup (or BIOS), a corrupted system partition, a dying disk drive… The solution presented here will not work for all situations but it will surely solve the problem if the system partition has been damaged. Be careful as the commands described here could damage your windows installation even more if they are not used properly so do it at your own risks and be sure to understand what you are doing. If you are not familiar with the concepts of disks and partitions or feel unsure about reproducing these steps, ask someone with good computer skills to help you. As always, the author and the website decline any responsibilities about the consequences of trying to reproduce these steps.

I received the dreaded “Reboot and Select proper Boot device…” error message a few days ago after modifying the disk partitions (not a good idea). I could still see the Windows files, the programs folders or my documents by using a different boot device. That meant that the disk was still working properly and that the boot partition was damaged so that  Windows 10 wouldn’t start up anymore. I could have restored a disk backup as described in a previous tutorial, but I was pretty sure that I only needed to repair the system partition files so I decided to document how I did it in this tutorial in case anyone needs to do something similar.

In order to reproduce the steps described in this tutorial you will need:

  • Either a Windows 10 installation media (it can be a DVD or a USB flash drive) or a Windows 10 Recovery media (again either a DVD or USB flash drive). You can create these media using an other computer or you can borrow them from a friend.

I used a Windows 10 Recovery Flash drive in this tutorial but I could have used a Windows 10 installation media instead. The commands used are exactly the same but the steps needed to access the “Troubleshoot” options are slightly different (as you will see in the tutorial).

So let’s see how I did it:

1) First I inserted the Windows 10 Recovery Flash drive into one of the USB ports.

2) Then I restarted the computer and I pressed the F11 key (the key used for that purpose on my computer) to change the boot order.

F11 for Boot Menu
F11 for Boot Menu

Please note that the key used to enter the boot menu depends on the motherboard UEFI Setup (or BIOS). That information that is generally displayed during a few seconds before loading the operating system. You might have to check the motherboard documentation in order to see how to change the boot order if you are not familiar with the UEFI Setup (or BIOS).

3) I selected the USB Windows 10 Recovery Flash drive (the USB: KingstonDataTraveler entry in the following screenshot) as the boot device:

select Boot Device
select Boot Device

4) The computer started to boot using the Windows 10 Recovery media:

Recovery starting up
Recovery starting up

5) And after a few seconds it asked me to select the proper keyboard layout:

Choose keyboard layout
Choose keyboard layout

The “See more keyboard layouts” button gives access to additional keyboard layout in case of need.

6) After choosing the proper keyboard layout I was asked to choose one of the options displayed in the following screenshot. I wanted to access the advanced options so I clicked the “Troubleshoot” button.

Choose a Recovery Option
Choose a Recovery Option

If I had used a Windows installation media, these first steps would have been slightly different. After choosing the language and keyboard layout, I would have clicked the “Next” Button:

Windows setup
Windows setup

Later, I would have clicked the “Repair your computer” button on the bottom left (do not to click the “Install now” button as you do no want to reinstall Windows 10):

Repair your computer
Repair your computer

And after that I would had access to the “Troubleshoot” option.

Troubleshoot
Troubleshoot

7) An “Advanced Options” window appeared after I clicked the “Troubleshoot” button. There was a “Startup Repair” button so I decided to give it a try:

Startup Repair Option
Startup Repair Option

8) Unfortunately it couldn’t repair my computer startup, so I clicked the “Advanced Options” button to navigate to the previous screen:

Startup Repair couldn't repair
Startup Repair couldn’t repair

9) This time I clicked the “Command Prompt” button in order to be able to launch the commands needed to repair the Windows 10 startup:

Advanced Options Command Prompt
Advanced Options Command Prompt

10) A command prompt window appeared as a result :

Command prompt
Command prompt window

11) The first command I needed to execute was “diskpart”. This command is used among other things to get the list of disks, partions and volumes:

diskpart command
diskpart command

12) I entered the “list disk” command to access the list of disks detected by the computer:

list disk command
list disk command

13) I knew by its size that the second disk of the list, the one identified as “Disk 1” had the installation of Windows 10 Pro. I entered the “sel disk 1“command to select it:

Select disk 1
Select disk 1

14) I wanted to see the disks volumes so I typed “list vol“:

Volumes list
Disk Volumes

The volumes displayed here were (they would be different on your system):

  • “Volume 0” assigned to letter C: was used to store backups.
  • “Volume 1” assigned to letter D: had the installation of Windows 10 Pro (I would need its drive letter later).
  • “Volume 2” assigned to letter E: was a small 1 GB partition.
  • Volume 3” was not assigned to any letter. This was the volume I was looking for: it was hidden, it had a FAT32 file system and its size was only 100 MB. Its label, EFI, was an other clue but it could have been named anything else.
  • “Volume 4” was the recovery media I was using.

Only “Volume 3” had the characteristics I was looking for so it had to be this one. I typed the “sel volume 3” command  in order to select it as the current volume. Be sure to choose the proper volume if you are reproducing these steps. It doesn’t have to be “Volume 3” on your system but it will be a small hidden FAT32 volume.

Select volume 3
Select volume 3

15) I needed to assign a drive letter to the volume before being be able to format it and to copy the system partition files. I chose letter Z: but I could have used any other unused drive letter. The command used for that purpose was “assign letter z:“.

Assign letter z:
Assign letter z:

16) I exited diskpart using the “exit” command:

Exit diskpart
Exit diskpart

17) I typed “Z:” to select volume Z: as the current volume and to verify that the drive letter had be assigned properly:

Use volume Z:
Use volume Z:

18) The next step was to format this volume. The format command would ask for the current volume name for security reason, I used the “vol” command to get it (the diskpart “list vol” command used previously provided that information too). The volume label was EFI in this example but it could been named anything else on your system. I entered the  “format Z: /FS:FAT32” command to format the Z: volume with a FAT32 file system. Be careful here: the “format” command will erase everything in the volume so don’t use the wrong volume!

Format volume Z:
Format volume Z:

19) The format command issued a warning and asked for a confirmation before proceeding (again be sure to format the proper volume as this operation cannot be undone):

Warning
Warning

20) The volume was currently in use (it was the current volume used by the command prompt) and it had to be dismounted before being formatted. As a consequence the “format” command asked if I wanted to force dismount it (if not it the format would had been aborted):

Force dismount volume Z:
Force dismount volume Z:

21) I confirmed it by typing “Y” and the format command asked for an optional volume name. I decided to name it “EFI” as before but I could have named it anything else. The “format” command finally ended formatting the volume with success:

Format complete
Format complete

22) I could now use the “BCDBoot” command to copy the system partition files from an existing Windows 10 partition. I had identified previously (in step 14 of this tutorial) that volume D: was the one with a Windows 10 Pro installation. So I typed the following command to copy the system partition files onto the Z: drive:

BCDBoot D:\Windows /s Z: /f UEFI

  • “D:\Windows” was the existing Window 10 installation folder.
  • The “/s Z:” argument was used to specify the system partition volume letter.
  • The optional “/f UEFI” argument was used to specify that I had a UEFI/GPT-based system. If it had been a BIOS/MBR-based one I would have used “/f BIOS” instead.
BCDBoot command
BCDBoot command

23) The boot files were successfully created, I closed the command window, I turned off the PC, I removed the USB flash drive, I restarted the computer and … Hurrah! … Windows 10 was booting properly now.

Turn off PC
Turn off PC

Conclusion:

The whole process took less than 10 minutes (including the time required to take the screenshots) and it allowed me to quickly repair the damaged system partition files that had led to the infamous “Reboot and Select proper Boot device…” error message. Once again, there are many different situations that could have led to this error message. The commands I used in this tutorial may not solve the issue with your system but they are worth a try if you understand what you are doing. In any case, every HDD or SSD will fail one day so be sure to backup them BEFORE it happens. You can see how I did a full disk backup using Acronis True Image here.

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