[ubuntu-za] Dualboot with Windows 10 and upgrade to 1703

[Charl Le Roux]

Just a word of caution to anyone who dualboots with Windows 10.

I recently installed the 'creator edition' update (1703) and Windows
deleted my Ubuntu partition and grub to the extent that I was not able to
recover it. I had to re-install.

It seems that Windows 10 attempted to convert my OS disk from MBR to GPT
and in the process ignored that fact that I had another OS installed. On
startup of windows it reverted to the old state, including MBR, but the
damage was already done.

I did the following to recover:
- Reinstalled Ubuntu- after which I was not able to boot Windows.
- I then converted the disk to GPT using gdisk utility (booting from live
CD)
- From live CD I had to chroot into my ubuntu to install grub-efi, map the
efi partition to /boot/efi, and update grub (which did not find the the
windows)
- I then changed bios to boot using UEFI
- Now I was able to start ubuntu from grub via uefi(on gpt disk)
- To recover Windows boot I had to boot from recovery usb, use diskpart to
assign a drive letter to the efi partition.
- Then I had to run bootrec /scanos, bootrec /fixmbr, bootrec /fixboot,
bootrec /rebuildbcd
- I was now able to boot into Windows again but no grub
- I was able to boot into Ubuntu from the BIOS UEFI selection screen and
installed grub
Then:
apt-get install --reinstall grub-efi
grub-install /dev/sda
update-grub
- Now all is well and booting faster than ever (assuming it's gpt and uefi)


What a desaster, it took be the best part of a day and a half to figure
this out. The above is not step by step but just what I can remember off
the top of my head.

My take away from this:
- Make sure our disk is GPT partition scheme if you dual boot with Win10
before you update to the 1703 version.

Hope this helps someone.

Regards




-- 
Charl le Roux
Mobile: +27834520405
Email: charl.leroux at gmail.com
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