Windows 10: Reinstalling W10 on a GPT disk from a USB boot disk

I'm working on an HP laptop whose Windows installation has been damaged following the user falling for the Microsoft scam. Having made several attempts at repairing the damage without success, the obvious solution is to reinstall Windows.

And here's the problem: I have a Windows 10 boot disk on a USB stick; in order to get the BIOS to see it, I put the PC into legacy mode, then boot from the stick. On attempting to install on the appropriate partition, I get the message that Windows can't be installed there, as it's a GPT disk.

Since Windows was already installed there, what's the problem? Do I need a special version of the boot disk? A little research seems to suggest that I need to convert the disk to MBR; this seems counter-intuitive, since GPT is the more modern system, and the PC and its damaged Windows 10 installation were running satisfactorily prior to the damage occurring.

Any advice much appreciated.

:)

 

Windows (10) cannot be installed

W10 cannot be installed via clean installs on some types of HD. See quote from original post:

"... I cannot recall the exact error message while trying to install W10 (clean) except that it took exception to / desired one or the other i.e. EFI vs a GPT disk? ..."

Originally I did install W10 clean. But it became very unstable and froze at the next bios boot screen. Luckily I had two partitions - W7 and W10. I had a boot repair USB which allowed me to boot into W7. From there I tried many things - W8.1 would not
upgrade to W10 because I believe it did not like the GPT partition.

I had to install W8.0 and this allowed me to upgrade to W10. This in now almost a clean install. But don't count on doing a clean install from an upgrade if you have a GPT partition!

John

 

Is it possible to install Windows 10 in UEFI mode using the original USB stick?

Hi,

I would like to know whether it is possible to use the USB stick supplied with the full version of Windows 10 to install the system on a disk configured to use the GPT (rather than MBR) partition style.

I am asking because the guidelines from Windows Setup: Installing using the MBR or GPT partition style stress that to install Windows on a UEFI disk, it is necessary to boot the setup medium in UEFI mode as well. However, the original
USB stick seems to be using the MBR partition style. In any case I can't boot from it when the PC is configured to boot first from a "UEFI USB Key"; booting only succeeds when the firmware is set to boot first from a "USB Key". But then the installer converts
the system disk to MBR even if it was previously set to use GPT.

Does this mean that in order to install the system on a GPT disk, I cannot use the original USB stick, but I need to download the Windows 10 ISO file and write it to another USB stick formatted using the GPT partition style?

Best regards,

Wojtek

 

Your getting that as you set it to legacy mode. Have you got the latest iso with the latest version of windows no sense putting an old version on

 

How did you make the USB flash drive? I'm willing to bet your answer is going to be, "With RUFUS"

 

Why are you enabling legacy mode? Have you tried using the boot menu (in UEFI mode)? Usually F12 at boot, you want to select the UEFI boot from USB.

 

The OP posted:

I suspect the USB flash drive is formatted as NTFS which most computers will not boot from in UEFI mode and that it needs to be created again using FAT32.

 

Some older bioses do not boot from usb drives in EUFI mode.

So trick here is to use rufus with downloaded iso and select 'mbr partition scheme for UEFI'

This allows you to boot usb in legacy bios mode BUT installs Windows 10 in UEFI/GPT mode.

After installation, reset bios to UEFI mode.

 

I'd be interested to know which chipsets those BIOS's were on because I've not run into a UEFI BIOS (Gigabyte boards) that didn't run a USB drive. I'm going to assume if the BIOS is UEFI, it will run a USB stick. I'm also going to guess the laptop isn't so old that it wouldn't support a USB flash drive.

At any rate I'm with NavyLCDR on it being a format issue. On the other hand it could be a "secure boot" issue where secure boot "may" need to be disabled. I've never had to do this myself in reinstalling or upgrading my system, but some do recommend it be disabled for Windows installs...

• The hidden challenges of booting from a USB flash drive

 

For HP, "F9" on power up allows selection of boot device. No changes needed to BIOS.

 

Never ASSUME anything. If you get it wrong, it can make an ASS of U and Me.

What I stated is true on some older pcs as they did not all implement the UEFI standard properly. I had a Sony where that was the case.

Anyway, if OP uses Rufus and selects "mbr partition for UEFI install", that works on any UEFI pc that can legacy boot as well.

 

Given your statement, I'd ask what "older pcs" didn't implement UEFI properly? Perhaps a definitive answer would help the OP, seeing they may have such a PC?

Oh, and If you're going to caution me on assuming, than I'm going to caution you on guesswork as fact.

Peace *Cool

 

Thanks guys for replies so far. Update: Downloaded Windows 10 ISO, Created USB stick (FAT32) with Rufus, selected "mbr partition scheme for UEFI". Attempted to install on Windows partition. Same result as before - can't install on GPT partition. This was with BIOS set to legacy mode. Tried again with BIOS set to UEFI mode, no USB boot option available. So - no further forward.

Any more suggestions?

 

I am really puzzled why that did not work - is your iso 32bit?

This will work - install from hard disk instead.

Look at this tutorial:

Windows 10 Recovery Tools - Bootable Rescue Disk - Windows 10 Forums

In post 1, go to section

How to add Recovery Media as Bootable Option

and follow instructions.

 

Suggest you follow NavyLCDR suggestions in leaving Rufus alone and keeping things simple...

It would also help to know the PC specs - motherboard? If Laptop, specific model? This would eliminate the guesswork as to whether the PC supports "booting from a USB stick".

Thanks.