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I originally had Windows 10 installed on an SSD, and Ubuntu 18.04 installed on another. I recently upgraded my machine and installed a 2TB M.2 drive, which I partitioned with Windows on one half and Ubuntu 20.04 on the other (but left the other drives in the machine) with GRUB installed on the M.2 drive. At this point GRUB allowed me to boot into the new Windows and Ubuntu partitions on the M.2 drive without a problem, although when booting into windows I had to select which Windows installation to use (the new one or the old one on the SSD).

I then formatted the SSD containing the old Windows installation, but then when selecting Windows from the GRUB menu I got an error message telling me there was nothing on the drive (I guess the Windows bootloader must have been installed on the old drive?).

I ran boot-repair from a USB stick to see if that would help, but that has just removed Windows from the GRUB menu entirely, so I have no way of booting into Windows.

Could anyone advise how I can boot into the Windows installation? Do I need to somehow reinstall the Windows bootloader on the partition? Or can I just configure grub to point to the Windows partition?

Thanks

cltweedie
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  • Post link to summary report from Boot-Repair in your question above. Windows 10 on updates likes to turn fast start up back on and then the Linux NTFS driver will not mount the NTFS partitions, so os-prober will not see them. Boot-Repair just run the update-grub and when Windows not seen, removed it from menu. Fast start info:http://askubuntu.com/questions/843153/ubuntu-16-showing-windows-10-partitions & https://askubuntu.com/questions/145902/unable-to-mount-windows-ntfs-filesystem-due-to-hibernation – oldfred May 24 '20 at 14:39
  • Do you have an EFI system partition? Where is it? I am assuming you have these installed as UEFI. Your problem is I think with Windows and not Ubuntu. You have to repair the windows boot manager by using a windows USB. – VidathD May 24 '20 at 15:26

3 Answers3

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Grub 2 has the capability to auto-detect other operating systems and automatically add an entry to the boot menu for them. Since your setup has changed after formatting the drive, you should re-run the detection script using the following command:

sudo update-grub
Jaap Joris Vens
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For temporary solution you can still boot into windows using bios or one time boot menu. for updating the GRUB entry just run grub update from ubuntu which you have installed

Soumith Kukutla
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  • I can't boot into Windows from the BIOS or boot menu, I can only select the whole M.2 drive as a boot option, which takes me to GRUB. – cltweedie May 24 '20 at 13:17
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Issue

I had the same issue. When formatting a drive where windows was located it is possible that you delete the bootloader. Even when cloning the old drive with windows to a new drive there can be trouble with cloning the bootloader.

The problem with this is that the bootloader is deleted which makes windows unbootable.

Conclusion

It is as far as I have tried not possible to repair or reinstate the bootloader. A clean windows install has to be done.

Solution

When booting into linux you can see you're drives where windows is located.

  • Be sure to backup any files before you do the clean install.
  • Backup your linux if they are installed on the same drive.
  • Unplug your linux drive if its installed on a separate drive
    • Windows is not very kind to another os, so just to be sure.

After the clean install your data is lost, its not lost now its still accessible (Although not through windows).

Download the windows iso file and put it on a usb or cd (Program does that for you.)

Put the USB or CD in your pc and boot. Be sure to hit DEL (Or other key) to get into your motherboard BIOS. Change the boot order so that you're USB or CD is selected as boot drive.

Follow the steps of the installation.

After installation:

  • Plug back drive with linux back in pc if disconnected
  • Set back files on windows

Go into your linux os and:

sudo update-grub

Jan
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