grub didn't detect windows 10

**arnabsarkar** · August 20th, 2019

I had a dual boot of windows and ubuntu 12.04. Yesterday I installed ubuntu 18.04 and after restarting PC went to grub rescue, I used superGrub 2 to boot into ubuntu and installed and updated grub from there. But grub does not detect windows anymore. I can see and open windows using Super Grub CD. but cannot get it listed on the normal grub.

I also did a boot repair but it did not detect windows either.

This is the pastebin of the boot summary generated by boot repair : http://paste.ubuntu.com/p/vrdgrbq867/

I am unable to follow through the other related posts and can't get a solution to my problem. Please help me.
Thank You

**richard378** · August 20th, 2019

sudo update-grub in Ubuntu should work unless it is a old install and you have a Legacy Windows install and a EUFI Ubuntu install. Or vice versa. I don't understand the boot repair file I am not that expericneced. But it may be your problem from what I see. I think it installed Legacy Grub because you installed Legacy Grub for your Ubuntu. You have two boot entries for Ubuntu one is EUFI and one it Legacy and it seems the Ubuntu works with Legacy as that is how you installed it.

**oldfred** · August 21st, 2019

I have not seen grub installed in so many places. You should only have grub in one place.

You have a grub in the MBR, in sda6 & sda7's PBR - partition boot sector. All three for BIOS boot.
But then have sda6 & sda7 set for UEFI boot with grub installed to them. UEFI & BIOS boot modes do not mix well on same drive.

You have a MBR(msdos) drive, so Windows has to boot in BIOS mode.

You have two ESP - efi system partitions and only one allowed per drive for UEFI boot.
But Windows requires boot flag on the Windows partition with its boot files, so you cannot have an UEFI boot of Ubuntu on a MBR drive with Windows in BIOS boot mode.

Use gparted to move boot flag back to sda2 and temporarily install a Windows boot loader to MBR. See if Windows boots ok. Grub only boots working Windows, so important that Windows is ok.

Then install grub to MBR using BIOS boot only of Ubuntu live installer.

If able to boot Ubuntu installer in UEFI mode, you must have a newer system. Not worth converting now, but eventually probably better to reinstall newer Windows in UEFI boot mode & then Ubuntu in UEFI boot also. You also have to convert drive from MBR(msdos) to gpt, so major change & really good backups required.

**arnabsarkar** · August 21st, 2019

thanks for the response.
So will I have to install both OS again after converting drive to gpt to get a dual boot option other than using supergrub cd each time I'm to log onto windows?

sorry I'm really new to Ubuntu probably messed up the system myself trying to make it run.

thanks

**oldfred** · August 21st, 2019

No, you can dual boot but Ubuntu must also be in BIOS boot mode. And that just requires a full reinstall of grub. Easiest with Boot-Repair & its advanced mode.

Just be sure to always boot in BIOS boot mode, not in UEFI boot mode unless you want to convert to UEFI. And then you have to convert all installs.
How you boot install/repair media for both Windows & Ubuntu is then how it installs or repairs system.

First screens you see to know which way you have booted. But selection is in UEFI one time boot menu, often f10 or f12, check manual.
Shows installer with screen shots. Both BIOS purple accessibility screen & UEFI black grub menu screen
https://help.ubuntu.com/community/UEFI

**arnabsarkar** · August 22nd, 2019

sorry I'm a bit confused checked the advanced option of the boot repair and the UEFI column is already unchecked.
then I ran this code on ubuntu terminal:
d /sys/firmware/efi ] && echo "EFI boot on HDD" || echo "Legacy boot on HDD"

and it prompted "Legacy boot on HDD"

my system is: hp 15-ay007tx.

also I tried to use boot repair to run UEFI boot, it then prompted to boot the disk on UEFI, upon disabling legacy support from BIOS and booting in UEFI mode I get F03 boot device not found error.

I'm still using supergrub to boot into windows.

thanks

**oldfred** · August 22nd, 2019

Since Windows is BIOS boot mode, you need to always boot in BIOS mode.
If you booted Ubuntu live installer in BIOS mode, it should say Legacy Boot.
Do not use UEFI boot mode, unless you want to totally erase & reinstall Windows.

And if you have not done backups, do that first.

Did you move boot flag back to Windows bootable partition as that is the only way then that Windows will correctly boot using Windows own boot files.

You should either from Windows repair console or a Windows repair flash drive, restore the Windows boot loader to the MBR (fixMBR & fixBoot commands on repair console), so it will correctly boot in BIOS mode. If Windows fast start up is on, then grub does not recognize it.

Make sure your HP system is set to boot in Legacy/CSM/BIOS boot mode, not UEFI.

Once Windows is correctly booting & fast start up is off, then you can boot Ubuntu live installer in BIOS mode and install grub to MBR to boot both Ubuntu & Windows from grub menu.