Win 10 boot volume mirror fails: Boot configuration data could not be updated

Question

I'm trying to add a mirror of the C:\ volume in Windows, but Disk Management gives an error:

Disk Management

The boot configuration data of the system could not be updated.
Use bcdedit.exe to update it manually. Note that bcdedit.exe is not
available on Windows 2003 Server. Edit boot.ini or use
bootcfg.exe instead.

OK

Obviously we're not going to use bcdedit.exe to update boot configuration data - because nobody knows how (and also because that's not my question).

How do i make Windows Disk Management not fail to do what it needs to do?

Microsoft Windows [Version 10.0.18362.449]

Bonus Reading

• Keep getting BCDEdit errors trying to mirror system drive using Disk Management ^*
• No longer able to create a bootable software mirror ^*
• How to Mirror Boot Hard Drive on Windows 10 (Legacy or UEFI)

I like the particularly unhelpful answer:

You install is corrupt, suggest doing a clean install.
Or it is a bug, wait for microsoft fix it
then do a clean install.
Also do a clean install every 6 months.
Also switch to Linux.

Edit: The question obviously isn't about how to create a mirror. The mirror is created just fine (you can see it in the screenshot). Both drives in the mirror pair are Dynamic Disks, BTW.

This question is:

• what causes Disk Management to be unable to update the boot configuration data (on a fresh install of Windows 10 Professional)
• what can i do to make sure that Disk Management is able to update the boot configuration data

Because we all know that if the 1st disk fails, and someone tries to boot off the mirror disk, the boot sequence will fail. Using mirroring to mirror a boot disk has worked in Windows 1000, Windows XP, Windows Vista, Windows 7, Windows 8, Windows 8.1, and Windows 10 pre-this version.

How do i fix it?

Answer 1

According to the last link in your post, you should also manually duplicate the System Reserved partition using diskpart and manual copy. As you have not done this part, it's possible that this is the cause of the problem with bcdedit.

For UEFI/GPT Based Systems the procedure is as follows:

Step 1 : Get type and partition size

Enter these commands in diskpart:

select disk 0
list partition

The result might be similar to:

Step 2 : Create partition and assign drive letters

After deleting all partition on the target disk, use the following commands in diskpart to create the System and Reserved partition(s) and assign a drive letter to the EFI partition, on the secondary disk (DISK 1):

select disk 1
create partition efi size=99      (use your size)
format fs=fat32 quick
assign letter=t
create partition msr size=16      (use your size)
select disk 0
select partition 2
assign letter=s
exit

Step 3 : Copy the contents

Copy the contents of the primary EFI System partition of Disk 0, to the primary EFI System partition on Disk 1 by typing the following command in command prompt:

robocopy.exe s:\ t:\ * /e /copyall /dcopy:t /xf BCD.* /xd "System Volume Information"

The above is just a subset of the information in the article. A good reading of it is advised.

The two disks need to look identical. From the article: