Some info first:

  • I have 2 SSDs
  • Windows 10 is installed on disk 1
  • Ubuntu is installed on disk 2
  • Boot/BIOS is set to "Legacy" and not "UEFI"

First time I tried to install Ubuntu to the second disk I chose Something else in this menu, then created 2 mountpoints (for / and for /home) on disk2. However during the installation I got this error

The 'grub-efi-amd64-signed' package failed to install into /target/. Without the GRUB boot loader, the installed system will not boot.

When I clicked ok, the installation was aborted and a bug report opened (don't have the URL anymore). On this bug report was something written like "it will work if you select 'Erase disk and install Ubuntu'".

(Note that after this failure Windows could still boot).

So because of this the first thing I tried was to convert my Windows MBR to GPT. However executing mbr2gpt /validate always gave me: Cannot find OS partition(s) for disk 0 (also tried the other disks, didn't work too). Anyway I then decided to not continue pursuing this, because I don't really care if I have UEFI or not.

So I did the following:

Since I have the luxury of having an entire disk anyway, I restarted the installation, selected 'Erase disk and install Ubuntu', then selected the correct disk (yes I'm positive that I did ;) ) and the installation run through.

My Ubuntu can now happily boot.

However the GRUB menu does not appear and this also doesn't help:

patrick@patrick-ubuntu:~$ sudo update-grub
[sudo] password for patrick: 
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-4.15.0-32-generic
Found initrd image: /boot/initrd.img-4.15.0-32-generic
Found linux image: /boot/vmlinuz-4.15.0-29-generic
Found initrd image: /boot/initrd.img-4.15.0-29-generic
Adding boot menu entry for EFI firmware configuration

Anyway I'm still positive it should somehow be possible to still boot Windows right? Since I'm pretty sure that my original Windows 10 disk is still untouched.

However I have no idea how to proceed. Any help is appreciated :)


Boot report: http://paste.ubuntu.com/p/rVymP7m6tt/

  • Is Windows UEFI or BIOS? UEFI and BIOS boot are not compatible, so once you start to boot in one mode you cannot switch or grub can only boot other installs in same boot mode. If UEFI on gpt you must have an ESP - efi system partition. And if two drives often best to disconnect one when installing. askubuntu.com/questions/743095/… Post the link to the Create BootInfo summary report. Is part of Boot-Repair: help.ubuntu.com/community/Boot-Info
    – oldfred
    Commented Aug 21, 2018 at 21:26
  • It's BIOS. I just tested it: When I select my Windows Disk via the BIOS Boot menu (or what ever it's called) I can still boot windows :D Anyway I also added the boot report to the post.
    – KittyKat
    Commented Aug 22, 2018 at 5:17
  • It shows Ubuntu installed in UEFI boot mode on NVMe SSD. But Windows in BIOS boot mode in sda. You can reinstall Windows in UEFI mode or with gparted add a tiny 1 or 2MB unformatted partition on NVMe drive and uninstall UEFI version of grub and install BIOS version of grub. Easier with Boot-Repair's advanced options. If newer hardware which it must be if it supports NVMe, there may be some advantages to UEFI. See: askubuntu.com/questions/647303/… & askubuntu.com/questions/446968/legacy-vs-uefi-help Or boot from UEFI.
    – oldfred
    Commented Aug 22, 2018 at 14:16
  • Thanks for your input. I think in my case I'm happy with the solution that I can simply select a new boot device since it's installed on differernt Disks. I will add this as the answer.
    – KittyKat
    Commented Aug 25, 2018 at 15:20

1 Answer 1


So in my case the solution was simple:

It turns out on my SSD 1 Windows is installed in BIOS mode On My SSD 2 Ubunut is installed on UEFI mode.

Because of this GRUB will never recognize Windows and vice versa.

However for the simple solution is:

While booting I simply press F8 - for the list of boot devices to appear- and then select the correct HD. Depending on this choice it will either boot my Windows or my Linux. This obviously only works because Windows and Ubuntu are installed on complete different HDs.

For me this is good enough!

If you (the reader of this answer) really want to use Grub, have a look at the comments below my question.

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