How to fix the missing Windows partition during the Ubuntu dual boot installation

In some cases, when you try to dual boot Ubuntu and Windows 8, the Ubuntu installer doesn’t recognise your Windows partition. I ran into this problem while trying to dual boot Ubuntu and Windows 8.1 on my XPS12. During the install you are left with the option to format your whole disk. This is not what you want, because you will lose all your files.

This error is related to the partition table of your disk. In some cases a GPT leftover remains on your SSD or HDD. Your Windows 8 is installed with a MBR partition table, but a GPT table also exists. This is the one you see when you try to install Ubuntu. To delete this GPT leftover:

  1. Download a copy of FixParts: http://www.rodsbooks.com/fixparts/
  2. Run the Ubuntu live CD (or USB)
  3. Install FixParts by double clicking the .deb file
  4. Start a terminal and run: sudo fixparts /dev/sdb (change B in your disk letter. Use Gparted to find the right letter)
  5. FixParts will tell you GPT signatures are detected on the disk. Type Y to continue.
  6. To close FixParts type q, don’t save changes.
  7. Run the Ubuntu Installer!