Dual Boot - Win10 does not boot from Grub

palmleon

6/3/23, 3:27 PM

I am trying to dual boot Ubuntu 20.04 LTS and Windows 10 on a computer with Win10 installed by default.

My computer has two disks: an SSD, which holds Win10, and an HDD, which will hold Ubuntu. I have not touched anything in the SSD to be sure not to break Windows. So, I have installed Ubuntu in an empty partition of the HDD (Grub should be there, too).

The problem is: when I try to boot Win10 from Grub2 (Grub2 sees it), a Recovery Screen raises and I cannot do anything but reboot the system. Instead, Ubuntu works fine. What is really strange to me is that Windows 10 works when I select it as the first choice in the boot sequence.

I have already checked that:

Both Win10 and Ubuntu follow UEFI, use GPT partition tables and use AHCI to access the drives
Win10 hibernation and fast startup are disabled
Secure Boot is enabled: I have read that Secure Boot may raise problems (but I know it only since after setting up Ubuntu), but both the OSs use it, so I am afraid to break something if I disable it.

I attach here an image of the Recovery Screen I get.

The point is: if both Windows and Ubuntu work on their own, why I cannot use Grub for booting both of them?

This is the first time I try to configure a dual boot system, so it is possible that I am missing something important.

P.S: This is also my first question on Askubuntu, if my question does not follow the standards for any reason, please tell me :)

0 + 0

grub2

dual-boot

windows

ChanganAuto

6/3/23, 3:31 PM

Suggestion: Boot Windows and check again Fast Startup that should be disabled indeed but some feature updates tend to re-enable it. That done also make sure all pending updates are installed (reboot as many times it needs) and SHUTDOWN. Next boot Ubuntu and run `sudo update-grub`. Try then to run Windows from the Grub menu.

palmleon

6/3/23, 7:06 PM

Unfortunately, nothing changes. I have just tried.

oldfred

6/3/23, 8:03 PM

Grub also cannot boot Windows when UEFI Secure Boot is on. Currently the chain of security is not passed from grub to Windows, so not considered Secure. If you want UEFI Secure boot, just always dual boot from UEFI boot menu, not grub menu.

palmleon

6/4/23, 10:19 AM

Glad to know that the problem is due to Secure Boot and not to some error during setup... Just for curiosity, what would happen if I disabled Secure Boot? Anyway, thank you both for your replies :)

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Dual Boot - Win10 does not boot from Grub

TH: Dual Boot - Win10 ไม่บูตจาก Grub

RO: Dual Boot - Win10 nu pornește din Grub

RU: Двойная загрузка — Win10 не загружается из Grub

VI: Khởi động kép - Win10 không khởi động được từ Grub

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