Windows not booting after converting from mbr to gpt

TheViper · 05 Oct 2021

Basically I changed from mbr to gpt using minitool partition wizard because I wanted to change to uefi because boot times was getting long lately with legacy, and now windows isn't booting I get a black screen with underscore blinking on the top left side of the screen.

My mobo doesn't have an option to change boot mode but from what I read it activate uefi automatically when disabling csm, but when disable csm I get sent back to bios instead of the black screen

I want a solution that ideally doesn't delete anything but I can deal with deleting the c partition

Specs:
Asrock h81m hds
I5 4440
Gtx 950
8gb ram

Sven1458 · 05 Oct 2021

Convert Windows 10 from Legacy BIOS to UEFI without Data Loss | Tutorials (tenforums.com)

TheViper · 05 Oct 2021

Sven1458 said:

Convert Windows 10 from Legacy BIOS to UEFI without Data Loss | Tutorials (tenforums.com)

I think I already converted to gpt with minitool because after minitool asked to restart to continue the operations after finishing the windows stopped booting

steve108 · 05 Oct 2021

I would make a Windows 10 install USB using https://www.microsoft.com/en-us/soft...load/windows10
then try and boot from it and try the repair option.

AddRAM · 05 Oct 2021

Didn`t PW give you the warning message that your system may not be bootable if you change it ?

Did you create a Disk image with Macrium before you did this ?

TheViper · 05 Oct 2021

steve108 said:

I would make a Windows 10 install USB using https://www.microsoft.com/en-us/soft...load/windows10
then try and boot from it and try the repair option.

I will try it

AddRAM said:

Didn`t PW give you the warning message that your system may not be bootable if you change it ?

Did you create a Disk image with Macrium before you did this ?

No I don't think so

Nope don't have much space for image

NavyLCDR · 05 Oct 2021

You used Partition Wizard to convert the drive to GPT, but did you create a new EFI System Partition to boot from? I'm betting not. Microsoft's tool mbr2gpt also creates the EFI System Partition, it looks like MiniTool Partition Wizard does not.

TheViper · 05 Oct 2021

NavyLCDR said:

You used Partition Wizard to convert the drive to GPT, but did you create a new EFI System Partition to boot from? I'm betting not. Microsoft's tool mbr2gpt also creates the EFI System Partition, it looks like MiniTool Partition Wizard does not.

I'm pretty sure that it was one of the operations but in case it didn't how can I create one

steve108 · 05 Oct 2021

NavyLCDR said:

You used Partition Wizard to convert the drive to GPT, but did you create a new EFI System Partition to boot from? I'm betting not. Microsoft's tool mbr2gpt also creates the EFI System Partition, it looks like MiniTool Partition Wizard does not.

Convert MBR to GPT with MBR2GPT Tool in Windows 10 V1703 or Later

They don't mention anything about having to create EFI partition yourself here.

AddRAM · 06 Oct 2021

I`m not sure that you`ll get a small 16MB partition when you convert a drive from MBR to GPT.

I did not get one when I converted W10 from MBR to GPT using the command line on the X299.

And I did a test with a spare Samsung 850 on the Z170, I put my latest image from my 860 Pro onto the 850 Pro, then I used AOMEI Partition Assistant Pro and converted it from MBR to GPT successfully, but it does not have the small 16MB partition and boots fine.

I got my 980 Pro 500GB Sunday, and I made my W11 installer a few hours ago. I believe doing a clean install will make the correct partitions.

Both of my MBR partitions were marked Active and had the System files written to them, I don`t let windows create a SR partition when I install on a MBR drive, that may have something to do with why I didn`t get a 16MB partition.

This is a shot of a UEFI clean install of W10 I did awhile ago, everything was correct and on unallocated space.