Ubuntu – Windows 10 update broke the MBR / GRUB

dual-bootgrub2

After I ran Windows 10 update this afternoon my partition table broke… I had dual boot with Windows 10 and Ubuntu 14 with Grub as the boot loader. The error that came up was "Error no such partition, Entering rescue mode… grub rescue>". I googled it, found out about the boot-repair ISO, installed it on a USB, ran the repair, got this report, but still no luck:

http://pastebin.ubuntu.com/23833420/

Now the boot skips Grub entirely and goes to Windows boot manager which fails with "The boot configuration data for your PC is missing or contains errors". So now instead of dual boot I have zero boot. Thanks Microsoft.

Anyway can you guys help me interpret the disk info in the pastebin link? I don't remember my partition configuration but I believe Ubunut had slightlty less disk space than Windows. Questions I have:

  • Is the Ubuntu partition still there? Could it be the one named "Extended"? (sda4)
  • Where would GRUB be? Gone? Can it be reinstalled? how?

I don't really care about the Windows partition anymore, but it would be nice to rescue Ubuntu.

Best Answer

You got bit by the notorious Windows 10 Anniversary Update... and it deleted your Ubuntu partition.

Recovery is difficult, but search here on AU for testdisk, as some users have used this program to recover their deleted Ubuntu partition. See http://www.cgsecurity.org/wiki/TestDisk_Step_By_Step for more information.

If you can recover your deleted Ubuntu partition, you may still need to use Boot Repair to reinstall GRUB and make your machine bootable again. Search here on AU for Boot Repair or read the Community Help Wiki on Boot Repair to find out more info.

You'll need a bootable Ubuntu Live DVD to perform the above tasks.

To fix the Windows boot problem, you'll need to use the Windows repair/install disk. Once booted into Windows again, you may find that some updates have not completed... just let them run to completion. I'd recommend doing this repair last, because you don't want to overwrite any of the deleted Ubuntu partition.