Windows 10: drive needs to be formatted as GPT but BIOS is legacy and not UEFI

I'm basically having a similar issue where I'm trying install a clean W10 onto my previous SSD and Win10 does see the drives and starts loading but stops whiting a few seconds stating that my drive needs to be formatted as GPT but BIOS is legacy and not UEFI. Perform Diskpart and clean the drive then created a primary partition and it's listed as so but RAW and not NTFS or FAT32? What could be causing this issue. Now Win7 was previously installed onto that drive but should be gone since I perform a CLEAN on it, correct? Thanks

:)

 

Bitlocker with Windows 10 and EFI/UEFI Bios and Legacy Bios + MBR or GPT disk

Hello,

I've read alot online about all of the scenarios for bitlocker and using Windows 10 with TPM 2.0. I've read things that said bitlocker encryption is not possible if it's a Win 10 box with TPM 2.0 bios in Legacy mode. It must be UEFI/EFI to work. Is this
correct? Also in addition to this, I also read that you want UEFI + GPT formatted disk. Will encryption with bitlocker still work if you have say ... Win 10 UEFI + MBR formatted disk???? Or do have to have both UEFI + GPT disk format for bitlocker drive encryption??

I am hoping to clear this up.

Thank you!

 

Bitlocker with Windows 10 and EFI/UEFI Bios and Legacy Bios + MBR or GPT disk

Below is a document from Microsoft on the requirements.

you don't need UEFI if you have a TCG compliant BIOS.

So legacy mode yes you do need UEFI.

Doesn't say anything about MBR vs GPT but I am running bitlocker and it is GPT and have used GPT for all my drives with Bitlocker.

https://docs.microsoft.com/en-us/windows/securi...

Hope this clarify things.

 

Windows won't install on GPT formatted drive.


I had an HP laptop that had what I called hybrid UEFI. It had limited support for UEFI booting in that it would only boot the HP support tools as UEFI. The hard drive had to remain MBR partitioned, though, and the OS had to boot in legacy BIOS mode. I do not know if that applies to your ASUS laptop or not.

What are you attempting to install Windows 10 from? In order to install Windows 10 in UEFI mode onto a GPT partitioned drive, the Windows 10 installation media must be booting in UEFI mode as well. This is how to prepare a USB flash drive for booting. Note to format the partition on the flash drive as FAT32 to make it compatible with both legacy BIOS and UEFI:
Create a Bootable USB Flash Drive

9. To format the partition, type format fs=fat32 quick, and then click ENTER.

For step 12 of the above procedure you will mount the downloaded Windows 10 ISO file and just copy all the files and folders from the mounted ISO file to the USB flash drive.

The flash drive created above will be bootable with both legacy BIOS and UEFI. To make the flash drive bootable ONLY in UEFI mode, skip step 10 of the procedure which marks the USB flash drive partition as active. You can toggle the active flag with diskpart (and third party partition apps). Active flag on - bootable by legacy BIOS or UEFI. No active flag - bootable by UEFI only.

1. Open Command Prompt (Admin).
2. Type: diskpart
3. At the DISKPART prompt, type: list disk (This command will list all the disks that you have)
4. In the next prompt, type: select disk # ( # means the number of the disk which contain the wrong active partition )
5. At the DISKPART prompt, type: list partition
6. Use the command: select partition # (# means the number of the partition that you want to mark as active or not active)
7. Inactive the active partition with command: inactive
7a. To mark the partition as active, use the command: active

So, I would create the USB flash drive using the procedure above listed in the link to the Microsoft Technet, but skip step 10 - do not mark the partition as active. Then try to boot the computer from the USB flash drive. If your BIOS is not UEFI, then you will either get an error - no boot device, or you will get just a blinking cursor in the upper left corner of a black screen. In that case, mark the USB flash drive partition as Active and format your SSD with MBR partitioning.