I use diskpart and bcdboot to shrink the OS partition by 100MB, create a FAT32 partition in the empty space, use BCDBOOT to write the boot files to it, then change the partition ID to EFI system partition. You should be able to do it while booted into the Windows that is on "HDB". The only issue will be that you won't have a standard partition layout on "HDA", the partitions will be out of order.
Beginning in Windows 10, Microsoft reserved partition (MSR) partition size is 16 MB.
Add an MSR to each GPT drive to help with partition management. The MSR is a reserved partition that does not receive a partition ID. It cannot store user data.
This partition is not use for booting Windows 10 the EFI System Reserved partition is use for booting Windows 10.
The minimum size of EFI System Reserved partition is 100 MB, and must be formatted using the FAT32 file format.
Please boot your computer with Windows 10 Installation Media and from Windows Recovery Environment start the Command Prompt.
Please type below commands into Command Prompt and press Enter key.
Following commands will repair Master Boot Record (MBR), Boot Sector and BCD Store.
Code:Bootrec /FixMbr Bootrec /FixBoot Bootrec /RebuildBcd
Please post a screenshot of these three commands outputs.
If Windows 10 installed HDD missing a EFI System Reserved partition you can create one by following below instructions.
Please boot your computer with Windows Installation Media and from Windows Recovery Environment start the Command Prompt.
From Command Prompt execute below commands one at a time:
Use "List Disk" command to find out disk number assign to Windows 10 installed drive.Code:Diskpart List Disk Select Disk 0 List Partition Select Partition X Shrink desired=100 Create Partition EFI FORMAT FS=FAT32 LABEL="EFI" Assign Letter=W Exit bcdboot C:\Windows /s W: /f ALL
Replace number 0 zero with disk number assign to Windows 10 installed drive
Use "List Partition" command to find out Windows 10 installed partition assigned number.
Replace X letter with Windows 10 installed partition assigned number.
You may need to replace C: drive letter with Windows 10 installed partition drive letter.
I have to warn you Diskpart tool is very dangers so please make sure to execute Diskpart command carefully.
Last edited by FreeBooter; 02 Feb 2018 at 16:43.
Thank you everyone for the help. Unfortunately, I'm not at home right now, so I can't try the fixes you guys recommended, but I expect to be back home tomorrow and will be trying them out.
It's because Disk 1 in post #9 is Disk 2 in post #10 which is the disk with the fresh Windows 10 install, running Partition Tool. The disk I'm trying to fix is Disk 1 in post #10, which was not showing in post #9 for some reason, and began to show later when I changed some BIOS options (to boot from UEFI Only).Weird in post #9 the Disk 1 have a EFI partition but not at post #10, any how i have posted instructions for the OP to follow to create a EFI System Reserved partition
1) See if you can find a camera or smart phone camera to take pictures of the display so that we can view the results in the thread.
2) Open the website for the computer or motherboard manufacturer > enter the model > select the operating system > view drivers > post a URL or hyperlink into the thread
3) Create a bootable Windows 10 iso:
Download Windows 10
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