Windows 10 to 11, MBR to GPT, boot problems

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Windows 10 to 11, MBR to GPT, boot problems

Ryan Hawkins 40

Hi, I am not super knowledgeable with computer stuff, i am having troubles changing my disks to GBT so i can enable secure boot, and to download Windows 11 and play newer games like Battlefield 6 etc.

I have an old 120GB SSD (Disk 0), old 2TB HDD (Disk 1), and recent 2tb SSD (Disk 2). Recent updated parts, 4090super GPU, AMD Ryzen 5 5600X, and Asus Prime B550M-A Wifi II. I have 32gb ram.. Currently on Win10.

My friend helped me install them and he migrated Windows 10 onto the SSD as my 120gb was constantly full.

After checking some youtube videos on how to change to enable secure boot, I need to change my disk to GPT first.

Through admin CMD, I did - mbr2gpt /validate /Disk:2 /allowFullOS

It said it failed and same for my other disks.

I completely wiped my HDD and (through NIUBI) migrated OS and everything onto it as a back up as i think that's what my friend did last time. I assumed maybe deleting all partitions from my new SSD would allow me to change to GPT. But my new problem after migrating/cloning, Windows won't boot through the HDD as it comes up with a winload.efi file is missing, so i have to put the SSD back in to boot.

Through all this i also want to update to Win11 also. So not sure if there is a better way like a fresh download of Win11 onto a USB and somehow doing a clean install would make it an easier process to change to GPT?

Or if i am not even on the right track, any help would be appreciated

Ryan Hawkins 40 Reputation points

2025-10-21T23:33:28.6833333+00:00

Update: all works now. Thankyou Rez for the assistance.

For anyone reading having similar problems, here's what I did (took a bit of trial and error, I may have missed something or got it in the wrong order, this took me like 4 days after work trying to figure this out myself and with Rez):

Quick refresher of what started this was pc health check saying my pc was eligible for win11. Turns out it was the secure boot. Battlefield 6 didn't work also because of needing secure boot. Couldn't change BIOS settings because disks were MBR, not GPT. Admin CMD check said I couldn't change my disk to GPT. Rabbit hole of problems while I tried to fix it.

Fix that worked for me,, ((Disclaimer, I am a noob who just did this via learning from YouTube, Reddit and this forum. Do at your own risk))

-Download a fresh Win10 onto a USB

-backup all files/videos/pics etc and everything u want saved, i moved this to an external harddrive

-Download NIUBI free partitioner

-I have a 120gb ssd and a 2tb ssd (I have a hdd but is old so backup storage now). My C:drive is on the 2tb SSD currently.

(use the NIUBI manual website page to make sure you do everything right)

-delete all partitions and wipe the disk you want your fresh Win10 to be installed to. For me, my 120gb ssd. Delete all volumes, I think i made sure it said 'unallocated' in Windows disk management after I finished that step

-convert the disk to GPT using NIUBI

-once done, make sure u can disconnect your Internet whether it's unplug Ethernet or disable WiFi

-once completed, turn pc off, disconnect your disk that had your C:drive, disable/unplug internet, leave your fresh disk in, then plug in your fresh Win10 usb, turn the pc back on

-follow prompts, but you should be able to install onto your fresh disk that u just changed to GPT that is still in the pc

-create a new profile with admin, once you are back at the desktop, reconnect internet capabilities and sign in to microsoft.

-once set up enough, turn off pc, plug back in the drive you want to use for normal stuff. For me, my 2tb SSD (which originally had my Win10 and all my data)

-turn pc back on, but go to BIOS. Make sure it's still booting from your fresh install. And make sure all your Secure boot settings are sorted as this should work now. (check your motherboard, but for me I made everything UEFI only and disabled CSM)

-once back in, go to NIUBI, wipe/refresh the disk that had the old Win10 and data on it, delete all partitions and make a new fresh volume. Use NIUBI to convert to GPT. Follow prompts and should be good to go.

-use Windows pc health check again to check if your eligible. As long as your hardware is up to spec, it should say you're eligible. Which means you can install win11 whenever and should mean games like Battlefield 6 will work now

-I have just finished transferring all my files back, have installed win11, and battlefield 6 works

Good luck

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Answer 1

Hi Ryan,

Thanks for your replies. You got it correct!

-Your files are already backed up - good to go!

-BIOS/UEFI should be in UEFI mode, secure boot is enabled - good to go!

-2 TB SSD should be cleared - good to go

-HDD cleared - good to go

-120 GB SSD wipe and clean install for Windows 10 - good to go

The reason why I recommend Windows 10 is due to Windows 11 25H2 instabilities especially the updates that bricks PIN/passwords, mouse and keyboards, localhost blocks, start menu blank and so forth. You will need a Microsoft account to get the Extended Security Updates for Windows 10 (for free based on your location up until next year).

To create a bootable media for Windows 10 or 11, see this link: https://support.microsoft.com/en-us/windows/create-installation-media-for-windows-99a58364-8c02-206f-aa6f-40c3b507420d

Then when you're in the setting up of account/OOBE page in windows 10. Unplug your internet. Then create a local account and set it with admin rights. After setting it up and getting to desktop, sign in with your Microsoft account via Microsoft edge or Microsoft store.

See the link below as I have included snippets to get ESU for Windows 10:

https://learn.microsoft.com/en-us/answers/questions/5587513/how-to-permanently-get-rid-of-hello-pin-or-any-oth?orderby=helpful&translated=false

Then in the near future, you can upgrade to 11, just follow the link above.

Good luck, all the best and regards.

Ryan Hawkins 40 Reputation points

2025-10-20T20:42:24.3333333+00:00

Thank you. I've already got the Win10 ESU. I will download the Win10 fresh install on a usb. I'll unplug my 2tb ssd with original OS on it before I install.

Just wanting to understand, how come I have to turn the internet off and create a new profile?

Do I turn the internet back on once I get to desktop so I can sign in to my Microsoft account?

And once I've logged in and pc is booted on my fresh install, is it OK for me to plug 2tb ssd back in and wipe it clean?
Restee Miranda 14,030 Reputation points Independent Advisor

2025-10-20T20:59:49.0533333+00:00

Congrats on the ESU enrollment!

To turn off your internet - simply unplug the LAN cable at the back of your PC, if its wired. If wireless, you can disable the wifi adapter temporarily.

Yes, you need to turn on your internet as it's needed to sign in with your account.

For the 2TB SSD, yes, definitely.

Answer 2

Restee Miranda 14,030 Independent Advisor

Hi Ryan,

You got a good PC setup there. What I can see is that the EFI partition in the HDD is what messes the migration. The MBR2GPT command is my tool when I'm lazy to do a fresh install of Windows 11 from Windows 10 PCs. You just need to clean up the drive you are cloning from, TRIM it, even compact it.

It's best to a full clean wipe of all of your disks (2 SSDs and HDD) for a fresh start. If you already have a backup of your files.

Migration and cloning can sometimes be messed up. Cloning can miss copying boot partitions. Migrations being corrupted.

Cheers,

Rez

Ryan Hawkins 40 Reputation points

2025-10-20T00:51:46.7333333+00:00

Hey, thanks for your answer.

My 120gb ssd is clean,

2tb SSD is where everything is and I just copied it all to the HDD (OS didn't work on the copy though).

If I fully wipe the 2tb SSD, is that going to get rid of my OS/ability to boot too?

In the big ssd, I have a 120gb C:drive partition where the OS, and like 1.7tb partition is where my other stuff is. And there's a few other random partitions like recovery and stuff. Can I just wipe/unallocate the other partitions and leave the C:drive? Then will it allow me to change to GPT?

I'd have to go and buy a large portable drive to back up my data if I were to wipe all disks at the same time.

Sorry if I misunderstood! Still getting my head around what all this does haha
Restee Miranda 14,030 Reputation points Independent Advisor

2025-10-20T03:40:58.2033333+00:00

Yes, if you fully wipe the 2TB SSD, you’ll lose your OS and boot ability since the boot files are there too.

You can’t just delete other partitions and keep C:, because Windows also needs the system/EFI partition.

Options:

Best: Install Windows fresh on your 120GB SSD (GPT mode), then format the 2TB SSD for storage.

Use mbr2gpt /convert /allowFullOS to change to GPT without wiping, then switch BIOS to UEFI.

Back up your data before doing any of the above.

Want me to list the steps for reinstalling Windows on the 120GB SSD safely?
Ryan Hawkins 40 Reputation points

2025-10-20T04:22:15.8766667+00:00

Thanks again.

Yes please, I think reinstalling a fresh Windows on the 120gb SSD would be the best bet so i can do what I want to the other 2 larger disks.

It is empty but it still has its old partition and is still MBR. Can you also tell me how to refresh the 120gb SSD ready for fresh OS and GPT?

If this all works, and the BIOS let's me change to UEFI only, will the Win11 update be very easy?
Ryan Hawkins 40 Reputation points

2025-10-20T11:19:13.27+00:00

Here is what i am up to currently. I have backed up all my files/videos/photos etc onto an external hard drive. The 2tb SSD is ready to be cleared. the HDD is cleared. and I have changed the 120ssd to GPT (according to NIUBU).

I just need the assistance in putting a fresh Windows onto my 120ssd (is this Win10 first or 11?), so I can clear my 2tb SSD and change that to GPT.

All this so i can hopefully go to my BIOS and enable UEFI (disable CSM) and enable secure boot.

Hopefully i got all that correct

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Windows 10 to 11, MBR to GPT, boot problems

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