Ok, I booted my Windows 10 install disk and worked my way to the command prompt to work with Diskpart. The system disk that I MBR2GPT'ed shows that the EFI (fat32) and Windows partitions are OK, except that my expectation was that the EFI partition should show as active & system (as on my current working system). Diskpart is also indicating that the system disk is not bootable.
The BIOS screen above is a screen shot of your MB Manual. The wording may be different since I don't have your MB.
I suggest that you disconnect all external device (USB HD, USB Stick). Reset the BIOS to default (this will reset the UEFI firmware). Go back to Boot tab, hilite the first entry then select UEFI, on second box select Windows Boot Manager
I tried selecting UEFI in the first entry, however there is no 'Windows Boot Manager' choice listed in the drop down list. I have thrown in the towel and began a fresh install of Windows 10. The instructions in my manual for this motherboard are pretty much non-existent when it comes to UEFI/Legacy boot modes. Based upon what was reported by diskpart, I don't think that MBR2GPT works very well.
it works fine MBR2GPT | Microsoft Docs
UEFI installs do not use old active partition.
Some bioses auto select to boot in uefi or legacy bios based on how drive is set up.
MBR2GPT does not delete old system reserve partition automatically.
It is possible boot loader is getting confused. Post image of partitions on disk.
I re-initialized my SSD as an MBR disk and re-installed Windows 10. I am now running with most of the system that I had prior to running MBR2GPT. After the conversion to GPT, the partitions that diskpart showed included EFI and Windows 10 partitions, however diskpart indicated that the drive was not a boot drive and did not show the Windows partition as 'boot' nor the efi partition as 'system'.
I will create a UEFI flash drive, and see if the BIOS auto selects to boot in UEFI mode - I know that it definitely boots in legacy mode.
Please update the system specs in the "My Computer" section:
How To Fill Out Your System Specs
System Specs - Fill in at Ten Forums:
System Specs - Fill in at Ten Forums General Tips Tutorials
In the left corner below in your post you find 'My System Specs'.
After clicking it you can find a link a little below that says 'Update your System Spec', click on this link to get to the page where you can fill in your system specs.
System Info - See Your System Specs - Windows 7 Help Forums
When you power on now what do you see?
Can you boot to wall paper/splash screen or desktop?
If you can please download and install mini tool partition wizard and post an image into the thread.
MiniTool Partition Wizard | Best partition magic alternative for Windows PC and Server
Take Screenshot in Windows 10 General Tips Tutorials
If you cannot boot to windows please create a bootable windows 10 iso:
Download Windows 10
Use this link to find the applicable keyboard key to boot to the USB external drive.
List of PC brands with their corresponding hot-keys
If it's a custom computer change the bios boot order so that the USB drive is on top.
Let us know if you can boot to the windows 10 iso advanced troubleshooting menu.
Ok, after rebuilding my Windows 10 system, I successfully converted my MBR-based system disk to a GPT- based system, SUCCESSFULLY using a combination of diskpart & gpt-fdisk. I used this method for a previous system successfully, but was lazy on my system thinking that a single command (MBR2GPT) would be easier and less prone to error.
BTW, my MSI motherboard (h61m-e23) auto selects UEFI/BIOS based on the format (MBR/GPT-EFI) of the bootable device. This information is NOT contained in the documentation provided by MSI. Based on Cereberus' comments, I created bootable MBR and bootable GPT/EFI USB sticks to test his second sentence.
Should have used MIni-Tool Partition Wizard
How to Convert MBR Disk to GPT | MiniTool Partition Wizard Tutorial
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