No bootable device after convert gpt to mbr

Question

Sorry for my bad English. I converted my disk from gpt to mbr to reinstall window 10 in my laptop (acer) with a usb boot yesterday, and i changed bios from uefi to legacy too. I suceed. After that, i started my laptop and it had a black screen with "exting PXE rom" but my laptop still work nomally. I searched google for the cause. Then, I used the usb boot to change the disk from mbr to gpt and i change bios from legacy to uefi, hope it will solve the problem. After that my laptop has "no bootable device" screen. I decided to change the disk back to mbr, and changed bios to legacy then my laptop had black screen with "No bootable device – insert boot disk and press any key". I coundn't open the boot menu with F12 button too. Please help me, and sorry for my bad English

Answer 1

Hello, my name is Gaston, I am an independent consultant.

I tell you that this problem occurs when the BIOS does not recognize the system's boot drive.

Windows 10 requires a GPT-style partition and booting in UEFi mode.

What is the software used to create the system image?

Try re-enabling UEFI mode and converting the disk to GPT.

Then use the USB bootable drive again to start the Windows installation boot.

When it starts up on the screen, select Language, Printing and Architecture and select Repair your computer.

Choose Troubleshoot> Advanced Options> Command Prompt and run the following commands:

bootrec /fixmbr

bootrec /fixboot

bcdedit /export c:\bcdbackup

attrib c:\boot\bcd -h -r -s

ren c:\boot\bcd bcd.old

bootrec /rebuildbcd

At the end of the process, you should see:

"Browse all disks for installation"

"Total Windows Installations Defined: 1"

Confirm the action and then restart your computer.

Then check.

Greetings.

Answer 2

Thank you for replying. I can re-enabling UEFI mode but i don't know how to convert my disk back to GPT right now because i can't open boot menu with F12 button to use the bootable USB and open the command prompt. Is there another way to open command prompt?

Answer 3

Hello again.

What is the software you use to create the USB bootable media?

What is the model of your pc?

Greetings.

Answer 4

Hi,

Switching from MBR to GPT and back and forth can cause a lot of problems...

GPT\UEFI uses a different partition structire on the HDD than MBR\Legacy and they are not interchangeable..

Your best bet at this point would be to select either UEFI Bios\GPT or Legacy Bios\MBR and

do a fresh installation of Windows..

Be sure to select your installation boot device as either the UEFI version, or standard version when you boot with it

to make sure your installation works properly.. Then select a Custom Install and delete everything on the HDD..

I would guess that at this point everything is so messed up that reinstalling Windows would be the easiest,

if not the only way to go..

Answer 5

I used the media creation tool from microsoft to create the USB bootable and my pc is laptop acer aspire A515-51G