GRUB Correction

After installing Windows (and if your GRUB failed) you need boot with LIVE CD/FLASH and run in cmd:

I have two LIVE CD/FLASH: 4Gb (Linux iso) and 8GB (Windows iso). I need to use 8G with windows iso.

bcdboot c:\Windows /s c: /l en-us

In case of error, correct it as written in this paragraph: https://papa31.github.io/hm/docs/new-disk/partitioning-new-disk/#single-windows

After that you need to reboot, enter into the BIOS/UEFI and change the boot order.

The Newest Way to Repair

 -------- Boot (tab) -------------

...
# 1     [P0: P3-256]
# 2     [UEFI OS (P0: P3-256)]
...

HARD DRIVE BBS PRIORITIES (subsection)
# 1     [P0 P3-256]
# 2     [NE-512]
...

info

If after sudo update-grub you get ouptut with this line at the end:

...
Windows Recovery Environment (on /dev/nvme0n1p1)

It's ok. Your GRUB menu is setup correctly. Reboot and try starting Windows via GRUB.

Old Way to Repair

Set the first UEFI option to:

P1:PS-256 (or P0-256 what disk first doesn`t matter)

And set second UEFI option to:

OS UEFI P1:PS-256

Here main goal is installing GRUB without detection Windows.

Reboot Linux, open terminal and run:

sudo update-grub

Reboot again and change second boot option to:

P1:PS-256 (first option need to be the same: P1:PS-256)

Reboot. You should see grub table menu. Choose linux start.

Then, open terminal again and repeat previous command:

sudo update-grub

After that command you should see detected Windows.

~ $ sudo update-grub
[sudo] password for papa:
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-5.6.0-2-amd64
Found initrd image: /boot/initrd.img-5.6.0-2-amd64
Found memtest86+ image: /boot/memtest86+.bin
/dev/sdc: open failed: No medium found
Found Windows 10 on /dev/nvme0n1p1
done