Help - my PC can't boot after changing "Windows 8/10 Features" in BIOS

So, here's the update I promised.

I found some notes in a Word document I had created to record the steps I used to build my desktop back in 2017. They mention changing the SATA mode to "Intel RST Premium With Intel Optane System Acceleration" from AHCI. This was required for me to be able to create a RAID array for two of my data hard drives.

It appears that while in this "Intel lRST Preimum...." SATA mode, for some reason the M.2 drive wasn't being seen as a result of my BIOS changes yesterday. Changing SATA mode back to AHCI caused the M.2 drive to appear and I was able to boot into Windows 10 again. Everything is working okay.

So, I now need to decide if I'm going to risk "breaking" my PC again in order to be able to upgrade to Windows 11! I can see that my drives are using MBR, not GPT. (My notes actually state that if I ever re-install, I should switch to GPT).

Here's my drive setup:



As you can see I have a copy of Partition Magic, which I believe can convert MBR to GBP without losing all the data, but I'm going to schedule some backups first.

milleniumaire said:

As you can see I have a copy of Partition Magic, which I believe can convert MBR to GBP without losing all the data, but I'm going to schedule some backups first.

Your BIOS MUST be able to boot as UEFI-GPT

Please edit your profile with ALL your hardware specs. It will help us to help you
System Specs - Fill in at Ten Forums


Converting a boot able Legacy-MBR to GPT will make it un boot able.
Windows not booting after converting from mbr to gpt
A UEFI-GPT drive needs a EFI Fat32 partition that most programs don't create.
The way to convert a boot able Legacy-MBR to a boot able UEFI-GPT is to use MBR2GPT.exe
Convert Windows 10 from Legacy BIOS to UEFI without Data Loss

Follow this steps:
- Detach (SATA or power cable) drive 1 & 2 from the MB
- Boot from a USB Win 10 installation drive
- On the first screen press (Shift+F10) to launch a CMD window.
- Type
MBR2GPT /validate (Instructs MBR2GPT.exe to perform only the disk validation steps and report whether the disk is eligible for conversion.)
- If OK type
MBR2GPT /convert (Instructs MBR2GPT.exe to perform the disk validation and to proceed with the conversion if all validation tests pass.)


Restart, enter BIOS and change the boot mode from Legacy-MBR to UEFI-GPT.
If it boots fine, shutdown and reconnect drives 1 & 2 to the MB

Megahertz said:

Your BIOS MUST be able to boot as UEFI-GPT
Please edit your profile with ALL your hardware specs. It will help us to help you

Thanks for the links. I will have a read and decide if I'm going to go ahead with these changes to my system, after first taking a full backup

At the moment I'm in no rush to upgrade to Windows 11 and there's even less inclination to do so given the changes I need to make to my system, which is currently working perfectly and meeting all my needs!

I have added my hardware specs as you have asked.

It's been a couple of months, but I have now decided to go ahead and convert my drives to GPT so that I can change to UEFI and turn on secure boot, ready for Windows 11.

Imagine my surprise when I ran "mbr2gpt /validate" (offline), to receive the following issue:

MBR2GPT: Attempting to validate disk 2
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
Disk layout validation failed for disk 2

Here's what Disk Management shows for my drives:



Originally, Disk 2 had 4 Primary partitions, so this morning I changed Programs (G:) to Logical as I'm aware to convert to GPT, only 3 Primaries can exist.

Any thoughts on how I can fix this issue? The error message isn't exactly helpful.

milleniumaire said:

It's been a couple of months, but I have now decided to go ahead and convert my drives to GPT so that I can change to UEFI and turn on secure boot, ready for Windows 11.

Imagine my surprise when I ran "mbr2gpt /validate" (offline), to receive the following issue:

MBR2GPT: Attempting to validate disk 2
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
Disk layout validation failed for disk 2

Here's what Disk Management shows for my drives:



Originally, Disk 2 had 4 Primary partitions, so this morning I changed Programs (G:) to Logical as I'm aware to convert to GPT, only 3 Primaries can exist.

Any thoughts on how I can fix this issue? The error message isn't exactly helpful.

Run (as administrator):

Code:

reagentc /disable

Then delete the recovery partition. You should have left drive G: a primary partition. The extended partition that contains the G: logical drive counts towards the MBR 4 partition limit, so mbr2gpt would still fail.

NavyLCDR said:

Run (as administrator):

Code:

reagentc /disable

Then delete the recovery partition. You should have left drive G: a primary partition. The extended partition that contains the G: logical drive counts towards the MBR 4 partition limit, so mbr2gpt would still fail.

When I got your post I was already in the process of creating a Recovery USB drive prior to deleting the recovery partition, but I did incorporate your suggestion to disable the recovery agent, although many articles I read, don't mention that this needs to be done.

So, after deleting the recovery partition using Partition Magic, I found I was no longer able to get to the command prompt through Settings -> Update & Security -> Recovery -> Restart Now -> Troubleshoot, so it was necessary for me to reboot from the Recovery USB drive I had just created, which gave me a command prompt.

Disappointingly, I still got the same error!

Further Googling talked about reducing the size of the partition to free up a couple of hundred megabytes at the end of the disk, so I tried this. I noticed, that running MBR2GPT /validate in the offline command line (via boot from USB) was reporting an issue with disk 0, not disk 2, which contains the OS! So, I included the /disk option and got the following results:

Code:

X:\windows\system32>mbr2gpt /validate /disk:0
MBR2GPT: Attempting to validate disk 0
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
Disk layout validation failed for disk 0

X:\windows\system32>mbr2gpt /validate /disk:1
MBR2GPT: Attempting to validate disk 1
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
Disk layout validation failed for disk 1

X:\windows\system32>mbr2gpt /validate /disk:2
MBR2GPT: Attempting to validate disk 2
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
Validation completed successfully

So, why does "mbr2gpt /validate" i.e. without the disk option, report disk 0?

I then decided to reduce the size of the primary partitions on disk 0 and 1. Both disks only have 1 partition.

Trying again (rebooting from USB), I get yet another result, which doesn't make sense:

Code:

X:\windows\system32>mbr2gpt /validate 
MBR2GPT: Attempting to validate disk -1
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
Failed to retrieve geometry for disk -1

I've absolutely no idea where it gets disk -1 from! This wasn't mentioned before.

Trying something else, I rebooted into windows and tried running mbr2gpt from an elevated command prompt and got the following:

Code:

C:\WINDOWS\system32>mbr2gpt /validate /allowFullOS                   (I obviously had to include the /allowFullOS option)
MBR2GPT: Attempting to validate disk 2
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
MBR2GPT: Validation completed successfully

Checking disks 0 and 1, still shows the "Disk layout validation failed for disk x" error. No idea why. Is this likely to be an issue? Do ALL disks need to be converted to GPT? I would have thought so.

As I was getting the successfully validation message for disk 2, I thought I'd give conversion a try, but no such luck:

Code:

C:\WINDOWS\system32>mbr2gpt /convert /allowFullOS

MBR2GPT will now attempt to convert the default book disk.
If conversion is successful the disk can only be booted in GPT mode.
These changes cannot be undone!

MBR2GPT: Attempting to convert disk 2
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
MBR2GPT: Trying to shrink the OS partition

After showing the "Trying to shrink the OS partition" message for about an hour, I gave up and cancelled the command.

Still not managed to convert to GPT! Surely, it shouldn't be this difficult?

I'm now at a loss again. Any thoughts on what is going on? Here's my current disk setup:

It's probably because of the extended partition with the logical drive G: in it. You can't have extended partitions and logical drives on a GPT disk.

To get your recovery environment back you just need to run:
reagentc /enable

It does not need a recovery partition.

When I used Ctrl+C to exit the "hung" MBR2GPT command, it gave the following error:

Cannot find room for the EFI system partition.MBR2GPT: Conversion failed

If by "extended partition" you mean logical partition, I converted it back to a primary partition, so there are no logical partitions on Disk 2!

Disk 2 now only has 3 primary partitions and some unallocated space.

Run the following commands then try again:

Code:

diskpart
select volume c
extend
exit