Cannot boot into Windows anymore [Solved]

[xaol]

update-grub does not bring Windows back into the Grub menu.

I tried again with LiveUSB ->Boot Rescue->Windows Boot loader, now with a different boot (from USB, not UEFI):
Now, it finds 2 bootloaders on drive (hd1,1)/bootmgr and on drive (hd1,2)/bootmgr. When I choose the one on the second partition, Windows starts (and occupies itself immediately with updates).
How to get it into the Grub menu?

have you tried mounting that second partition before running

Code: Select all

sudo update-grub

to see if that makes any difference?

[fehlix]

Have you tried as root user in terminal? update-grub

update-grub does not bring Windows back into the Grub menu.

I tried again with LiveUSB ->Boot Rescue->Windows Boot loader, now with a different boot (from USB, not UEFI):
Now, it finds 2 bootloaders on drive (hd1,1)/bootmgr and on drive (hd1,2)/bootmgr. When I choose the one on the second partition, Windows starts (and occupies itself immediately with updates).
How to get it into the Grub menu?

Yes, Windows on a MBR/DOS partition table installed, can only boot within BIOS/MBR boot mode - not with UEFI-boot.
Now first check again booted in MX Linux the normal procedure with the combo grub-install and update-grub this way:
Open terminal as normal user and run

Code: Select all

sudo dpkg-reconfigure grub-pc

It will show you two screens: On the first select/tick enable "OS prober ..."
Next -> select the boot drive (/dev/sda ), do not select partitions like /dev/sda2 etc, only the disk.
Normally the process would now find and add Windows boot entry to the GRUB menu.
If not, make sure you powered off from Windows without fastboot/fast-startup, which would prevent
os-prober to scan the windows partition for the windows bootloader...
... otherwise we might adjust some grub files, I guess.

[hako]

Mounting the Windows partition before update-grub did not make any difference.

sudo dpkg-reconfigure grub-pc

Yes! That brought back the 2 Windows entries in the boot menu.
Thank you!

[fehlix]

Mounting the Windows partition before update-grub did not make any difference.

OS-prober will temp-mount any detected drive and scan for known boot loader.

sudo dpkg-reconfigure grub-pc

Yes! That brought back the 2 Windows entries in the boot menu.
Thank you!

You may re-run this after a kernel upgrade, b/c kernel's post-inst will only trigger update-grub,
as os-prober has been disabled within update-grub by recent GRUB in Debian12/bookworm.