Booting UEFI and GPT on p6-2155a with Foxconn 2ADA mboard

[Prométhée]

Thanks @Paul_Tikkanen 
but I would have thought that you would have a solution for the problem described
in the end we simply come back to what I had proposed, the complete installation ..
damage

[Paul_Tikkanen]

You're very welcome.

As far as I know, you have to pay for commercial software to change the disk from MBR to GPT.

4 Ways| Convert MBR to GPT Without Losing Data in Windows 11/10 – EaseUS

I don't know of anywhere you can get free software to do that, and that Windows MBR to GPT command never worked for me.

[PB442]

Thank you @Paul_Tikkanen and Prométhée.

I was seeking to avoid a clean install from scratch of W10.  I have W10 operating already, and the machine is used by more than one person, and as you might imagine with a machine first configured 11 years ago, re-creating the software environment from scratch is no small thing. I upgraded the SSD because my son was running out of space to instal software (down to 30GB free on a 2TB drive even after I'd cleaned up the drive).  Most data files are on a NAS, not the system disk.

The BIOS is UEFI compatible, as I upgraded it to 8.17 (I think back in 2016), which was the BIOS shipped by HP for similar machines running Windows 8 (for which UEFI was an option).  It includes UEFI and legacy boot options, and includes option to configure for secure boot.

I am not averse to paying (within reason) for software to convert my drive, if it will work. Is there bullet proof software available that will reliably achieve conversion to GPT without data loss, and which doesn't require an engineering degree?   

I have AOMEI Partition Assistant Pro, for example, but when I sought to use it to convert the drive from MBR to GPT it reported error 215 suggesting my drive was too fragmented.  This seems to suggest  AOMEI is assessing my SSD drive as though it uses movable heads to read spinning magnetised platters. This seems outdated when many system disks these days are SSDs, and most new systems ship with SSDs. 

So I am currently stuck in my attempts using MBR2GPT (log at validation step says):

"Error GetOSDeviceVolume: Cannot get device data for entry. Error: 0xC0000024[gle=0xc0000024]
Error FindOSPartitions: Cannot get volume name for the recovery boot entry. Error: 0xC0000024[gle=0xc0000024]

and my attempts using AOMEI PA pro, returning error 215 which recommends defragmentation "or reserve free space of 2GB or more for the partition, and retry" even though I have 1.64TB unallocated space at the end of the disk (why I am looking to go to GPT).  I have posted to the AOMEI forum about that, but so far only response has been to defrag my SSD.   My SSD manufacturer counsels against degragging, as it doesn't improve performance worth a cracker and does use up finite write cycles on the SSD, shortening its life.

In then end seeking to convert to GPT (and UEFI) without starting from scratch (clean install of W10) is my problem, but I thought there might be  someone out there who'd met this before and found a way through,

Hope springs eternal...

[Paul_Tikkanen]

You're very welcome.

Since you already have a paid version of AOMEI disk partitioning software and it reported an error, unfortunately I don't know if a different product would be any better.

I have used the free version of AOMEI to do simple tasks like merging partitions and whatnot, but the free version does not allow for converting a drive from MBR to GPT, and since my situation is much different than yours, it was very easy for me to reinstall W10 in UEFI mode and reinstall my few programs and files and have things back to normal within two hours.

[Prométhée]

this help ?

https://www.windowscentral.com/how-convert-mbr-disk-gpt-move-bios-uefi-windows-10