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Thread: Grub not recongizing Windows 10 installation on another drive Dual boot

  1. #1
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    Unhappy Grub not recongizing Windows 10 installation on another drive Dual boot

    Hello all! I currently have two hard drives with Ubuntu installed on one and Windows 10 installed on the other. I have the manually select the drive to boot from in BIOS to select either windows or Ubuntu but i would like to be able to utilize Grub to boot into windows. I have tried to mount my windows 10 partition and run sudo os-prober but still nothing is recognized. I also have tried boot-repair and sudo update-grub I have included my boot summary from boot repair below, any and all help would be appreciated! Thank you for all your help!

    Thank you!!!!

    Edit: Link to the output of boot repair is below!

    http://paste.ubuntu.com/p/RmpjT3qH4p/
    Last edited by tombo007; August 28th, 2019 at 05:56 AM.

  2. #2
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    Re: Grub not recongizing Windows 10 installation on another drive Dual boot

    You need to post the link created when running the boot repair software rather than posting the output you have which isn't really helpful.

  3. #3
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    Re: Grub not recongizing Windows 10 installation on another drive Dual boot

    Thank you yancek! I edited my original post to include the link.

  4. #4
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    Re: Grub not recongizing Windows 10 installation on another drive Dual boot

    Alternatively, you can retry after activating the [Separate /boot/efi partition:] option.
    Falling back to read-only mount because the NTFS partition is in anunsafe state. Please resume and shutdown Windows fully (no hibernation or fast restarting.)
    You can use GParted which is on the Ubuntu install media to set the EFI partition (sda2) as active/bootable.

    The second problem is that you left your windows OS hibernated which is the default state. You need to boot windows and turn off fastboot and anything related to hibernation. Bear in mind that many windows updates will turn this back on and you will not be asked or notified that it is happening.

    After doing this, run sudo update-grub again from Ubuntu.

    THis should work although you have mixed an EFI install of Ubuntu with a Legacy/CSM install of windows. The other option would be to do a Legacy install of Ubuntu by creating a BIOD-Boot partition explained in the boot repair and below.

    [QUOTEGPT detected. Please create a BIOS-Boot partition (>1MB, unformatted filesystem, bios_grub flag). This can be performed via tools such as Gparted. Then try again.][/QUOTE]

  5. #5
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    Re: Grub not recongizing Windows 10 installation on another drive Dual boot

    Hey yancek, so I disabled fast boot and all things related to hibernation in windows but I am unsure how to set the EFI partition as active/boot able. I utilized GParted to add the eps and boot flags to the windows sbd1 EFI partition but now it seems like i have two EFI partitions(sdb1 and sda2). I tried to run sudo os-prober and nothing was out putted and also sudo update-grub seem to have done nothing. I re-ran the boot summary and attached the link below. let me know if I am doing anything wrong!Again thank you for all your help!
    http://paste.ubuntu.com/p/MP3MQwn8Hd/
    Last edited by tombo007; August 29th, 2019 at 07:48 AM. Reason: words

  6. #6
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    Re: Grub not recongizing Windows 10 installation on another drive Dual boot

    Setting the EFI partition as active/bootable would be done using GParted. First click on the EFI partition (sda2 in your case) to highlight it, then click on the Partition tab and click Manage Flags and click the check boxes for boot and esp.

    Your boot repair output near the top shows sdb1 with the standard windows boot files and below that it shows that partition as EFI. If you set the boot and esp flags for this partition (sdb1), change it back. An EFI partition on a 'dos' drive is useless. Windows won't work as an EFI install unless it is a GPT drive and your windows drive is not.

    After making the above changes, reboot Ubuntu and update grub again and watch the output for a windows entry.

  7. #7
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    Re: Grub not recongizing Windows 10 installation on another drive Dual boot

    UEFI grub will not boot a BIOS Windows.
    Once you start booting in one mode, you cannot switch. Or grub only boots other installs in same boot mode.

    UEFI does have a one time reboot to totally reboot the system, but grub does not have that capability. I think rEFInd does, but have no BIOS sytems to test.
    Generally best to have all systems in same boot mode.
    And if newer UEFI hardware, better to use UEFI installs.
    For more info on UEFI boot install & repair - Regularly Updated :
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to change to [Solved] when/if answered completely.

  8. #8
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    Re: Grub not recongizing Windows 10 installation on another drive Dual boot

    Thanks for all the input. So from my understanding, my sbd1 partition on my windows drive is a bios boot-loader for windows and my sda2 EFI partition is for Ubuntu? please correct me if i'm wrong. Could i possibly convert my sbd1 windows bios loader partition to an EFI partition and then I would fully be able to utilize grub?

  9. #9
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    Re: Grub not recongizing Windows 10 installation on another drive Dual boot

    As I understand it, converting Windows from BIOS to UEFI is complicated.
    You also have to convert drive from MBR partitioning to gpt partitioning which normally will work.
    And Windows in UEFI boot mode normally wants additional partitions.

    Really good backups required.
    Often easier to just reinstall.

    BIOS & UEFI Windows partitions, note system has totally different format & meaning between BIOS & UEFI
    https://msdn.microsoft.com/en-us/lib...=vs.85%29.aspx &
    https://msdn.microsoft.com/en-us/lib...Configurations
    new recovery partition just after main partition, recovery image, winre.wim, is typically between 250-300MB Plus free space
    https://docs.microsoft.com/en-us/win...ive-partitions

    Some older threads:

    Convert Windows from BIOS/MBR to UEFI/gpt.
    http://social.technet.microsoft.com/...n-to-uefi.aspx
    http://askubuntu.com/questions/86072...1327830_860729
    http://social.technet.microsoft.com/...n-to-uefi.aspx
    https://blogs.technet.microsoft.com/...ased-computer/
    http://www.sevenforums.com/tutorials...ndows-7-a.html
    http://superuser.com/questions/67624...-gpt-partition
    For more info on UEFI boot install & repair - Regularly Updated :
    http://ubuntuforums.org/showthread.php?t=2147295
    Please use Thread Tools above first post to change to [Solved] when/if answered completely.

  10. #10
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    Re: Grub not recongizing Windows 10 installation on another drive Dual boot

    Thank you so much oldfred you really are a guru and a saint for helping me out! I found this guide below on converting the MBR/Bios partition to EFI :https://www.windowscentral.com/how-c...efi-windows-10 do you recommend following it? I'm going to create a complete system image of my windows ssd and my other gaming ssd so i can recover it if all goes wrong before doing this.

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