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I've fallen victim to windows' aggressive handling of boot-ups. I have Ubuntu and Windows 7 side by side on my PC, and after I started the upgrade to Windows 10, I couldn't boot to continue the upgrade. Booting results only in Grub rescue prompt.

I've tried using boot-repair with no results (http://paste.ubuntu.com/12243604/) and I tried repairing the MBR with windows 10 installation iso, and it still doesn't fix the problem.

Since then I tried fixing the problem manually by enabling EFI in BIOS and i tried running the command bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi in Windows 10 installer, but nothing have helped so far.

I've also been looking around in the grub rescue menu, and all partitions shows as msdos partitions. And I can't find any boot partition through ls (hdx,msdosx), since they all show as unknown filesystems.

Both OS are 64-bit, ubuntu version is 15.04.


SOLVED: I managed to solve this through the windows 10 startup USB. I went into the command prompt and wrote the following commands:

bootrec /RebuildBcd bootrec /fixMbr bootrec /fixboot Exit (src: http://www.thewindowsclub.com/repair-master-boot-record-mbr-windows)

That wasnt enough though, as I continued to fiddle with he troubleshooting menu in the windows 10 repair menu. I turned UEFI off and after some random fiddling and being stubborn, the upgrade process has resumed.

Do note that this nukes ubuntu from the boot order!

  • @David6... done. – KhaaL Sep 1 '15 at 7:37
  • If/when you get the 'upgrade' to complete (and you have 'activated' Windows 10), start over. And use the default UEFI settings. See link below on dual boot install. This assume you also re-install Ubuntu. – david6 Sep 1 '15 at 8:30
  • @KhaaL with your explanations you restored the whole grub as it was before? I have the same issues and dont want to loose or reinstall ubuntu. Thx! – Obl Tobl Feb 7 '16 at 9:47
  • @OblTobl I never restored ubuntu, I nuked grub completly. – KhaaL Feb 8 '16 at 10:57
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I managed to solve this through the windows 10 startup USB. I went into the command prompt and wrote the following commands:

bootrec /RebuildBcd bootrec /fixMbr bootrec /fixboot Exit (src: http://www.thewindowsclub.com/repair-master-boot-record-mbr-windows)

That wasnt enough though, as I continued to fiddle with he troubleshooting menu in the windows 10 repair menu. I turned UEFI off and after some random fiddling and being stubborn, the upgrade process has resumed.

Do note that this nukes ubuntu from the boot order!

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Part of the problem is that Windows 7 doesn't use UEFI, and Windows 10 certainly does.

The Windows 10 'install/upgrade' utility (I really hesitate to use that word) somehow tricks the PC/laptop into changing its behaviour 'during the install/re-boot process'. It also overrides the boot order, with the 'failsafe' "Press key to boot from CD/DVD" to fix its own mistakes.

That means you need a quite recent BIOS or .. (You already found out what!)

PS: It also means picking legacy boot, the correct boot order, etc. isn't necessarily going to help very much.


Your problems are:

  • You need to complete the 'upgrade' to gain the 'activated' Windows 10 license. The only shortcut here is buy a license, and just install Windows 10.
  • You likely need to not go back to a 'factory install' of Windows 7 (as supplied by vendor), then start over. If you had an OEM install, then that brand of installer DVD (obtained/borrowed from wherever) will get you back to installed/activated with Windows 7. Then hunt down any missing drivers (from PC vendor's website), and don't forget to get all Windows updates. Then try again.
  • However, after 'succeeding' you will still want to do a 'clean install' of Windows 10. So start by getting the ISO file and creating an install USB (using Rufus: https://rufus.akeo.ie/), for any upgrades or re-installs. Lastly, follow these instructions: Installing Ubuntu Alongside a Pre-Installed Windows with UEFI
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Use Windows 10 in a Virtualbox environment if you have sufficient memory. Never use Windows as a your primary OS unless you absolutely have to. It is also a lot easier to backup your Windows 10 Virtualbox, all you have to do is copy a folder to an external drive. Furthermore, you can use your Windows 10 virtual machine on ANY computer with Virtualbox. Just my humble opinion.

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