[SOLVED] Can't boot to windows without CSM enabled after changing to GPT

[DerekForDayz]

Hey everyone,
I converted my boot drive to GPT from MBR, and the drive shows as GPT in disk management.
All seems good, until I go into the bios and disable CSM, and none of my drives then show up to boot to.

I would really appreciate any help with this, thanks!

 

[Colif]

The boot partition is still disk 0, you may have made Disk 3 into GPT which is C but the PC boots off the partition marked System & in an MBR situation, its also marked as Active.

 

[DerekForDayz]

The boot partition is still disk 0, you may have made Disk 3 into GPT which is C but the PC boots off the partition marked System & in an MBR situation, its also marked as Active.

I see, so is there a way to change the disk number of my windows ssd or is there something else I should try? Thanks again

 

[Colif]

Step 1. Boot your computer from a Windows installation disc or recovery disk. Press Shift+F10 in the setup to enter command prompt window.

Step 2. Run the commands below to shrink a partition to get unallocated space.

• Diskpart
• List disk
• Select disk X (X represents the disk number of the disk that needs an EFI partition)
• List partition
• Select partition N (N represents the partition number of the partition that needs shrinking)
• Shrink desired=500 (shrink the partition by 500MB)

Step 3. Then you can create EFI partition using unallocated space with the command below:

• create partition EFI size=200
• format quick fs=fat32 label="System"
• create partition msr size = 128

Step 4. After those two partitions have been successfully created, use the commands below to install boot loader and other applications needed.

• bootrec /fixboot
• bcdboot c:\Windows /s b: /f all

Step 5. Reboot your computer to see if it is fixed.

https://www.diskpart.com/windows-10/missing-efi-partition-windows-10.html
that should fix it, will need to go into bios after and change boot method

 

[DerekForDayz]

https://www.diskpart.com/windows-10/missing-efi-partition-windows-10.html
that should fix it, will need to go into bios after and change boot method

I will try this, thank you

 

[DerekForDayz]

https://www.diskpart.com/windows-10/missing-efi-partition-windows-10.html
that should fix it, will need to go into bios after and change boot method

Everything went well until I got to bootrec /fixboot, where I got the error "access is denied."

 

[Colif]

this is partially why i let other people do these...
diskpart
list disk
select disk 3
list vol
select volume no.
[NOTE– Replace the “<volume no.>” which is declared to have 100 MB storage. This partition contains the EFI (Extensible Firmware Interface) and usually formatted in FAT32 format.
assign letter=v
exit

now type this
v:
bcdboot C:\windows /s V: /f UEFI

How To Fix Bootrec /fixboot Access is Denied During Fix Boot Configuration in Windows 10

While fixing the Boot Configuration Data (BCD) on your computer you may encounter “Access is denied” message in command prompt window. If you are seeing this message you won’t be able to fix the boot related issue unless you take care of the problem first. To do so, follow these simple steps on...

thegeekpage.com

 

[DerekForDayz]

this is partially why i let other people do these...
diskpart
list disk
select disk 3
list vol
select volume no.
[NOTE– Replace the “<volume no.>” which is declared to have 100 MB storage. This partition contains the EFI (Extensible Firmware Interface) and usually formatted in FAT32 format.
assign letter=v
exit

now type this
v:
bcdboot C:\windows /s V: /f UEFI

How To Fix Bootrec /fixboot Access is Denied During Fix Boot Configuration in Windows 10

While fixing the Boot Configuration Data (BCD) on your computer you may encounter “Access is denied” message in command prompt window. If you are seeing this message you won’t be able to fix the boot related issue unless you take care of the problem first. To do so, follow these simple steps on...

thegeekpage.com

“Failure when attempting to copy boot files.”
Man this is going great. I looked up a few solutions to this and they said to set the drive as active, but I can’t due to it being non-MBR. Would reinstalling windows honestly be a better alternative to this?

 

[Colif]

reinstalling win10 with just the nvme attached would be a fix.

I was trying to avoid that one.