Booting troubles trying to have a dualboot Windows 10 - Ubuntu

manpreet Best Answer 2 years ago

I have a machine that had Windows 10 installed and I wanted to install Ubuntu alongside it. The partitions looked something like this:

Partition 1   2GB   NTFS
Partition 2   485GB NTFS
Partition 3   1GB   NTFS
Partition 4   13GB  NTFS

Partition 2 contained the windows installation and all the other partitions were empty. So I shrunk Partition 2 to about 100GB and proceeded to install Ubuntu using the live CD.

I adjusted the partitions manually when I was prompted to do so, so i deleted partitions 3 and 4 and replaced them with a partition which was going to serve as a common partition that can be accessed from both OS and a partition for linux. I replaced Partition 1 with a Linux swap partition because I thought it was empty and therefore irrelevant. So now it looks like this:

Partition 1  2GB   swap
Partition 2  100GB NTFS  /windows
Partition 3  348GB FAT32 /storage
Partition 4  50GB  ext4  /

I now believe that Partition 1 was used to boot Windows but I wasn't aware of it at the time. Anyway, I was surprised that Linux booted just fine but I wasn't able to boot into Windows.

So now I used the Windows 10 repair CD to try and fix it. Automatic repair yielded no results. So, from the command line on the repair CD, I reformatted partition 1 as NTFS and set it as active. Then I roughly followed this guide. I used these commands (in different orders at different points):

Bootrec.exe /FixMbr
Bootrec.exe /FixBoot
Bootrec.exe /RebuildBcd
bootsect.exe /nt60 C:
bootsect.exe /nt60 ALL

At some point I got all these commands to run without complaining and after exiting the command line, the repair menu gave me the option to boot Windows 10 (so I thought I had fixed the issue). However, whenever I selected that option the machine would try to boot and say something like Missing operating system

What makes it a bit more complicated is that partition 2 is actually not a primary partition but a logical partition inside an extended partition (I do not know why it is like that). That means I can't set the boot flag on it.

So now I would love to hear some suggestions on what I could try next. All my data is backed up, so that is of little concern. However, I'm not sure about the Windows key. My license has not been linked to a Microsoft account so I'm cautious to just reinstall Windows.