Ubuntu – Windows 8.1 doesn’t appear in GRUB2

I had Windows 7 (64-bit) and Ubuntu 13.10 (32-bit) installed on my laptop ASUS N53S. Unfortunately, a blue screen appeared on Windows each startup, but Ubuntu continued to run.

I decided to remove Windows 7 in order to install windows 8.1 (64-bit). It was a good reason to upgrade 🙂

I formatted my Windows 7 partition.

I changed from MBR to GPT with gdisk in order to be able to install Windows 8.1. and I succeeded in installing Windows 8.1.

When I start my computer, GRUB appears but Windows 8.1 doesn't appear, I can only run Ubuntu.

root@Clenet:/home/clenet# parted -l
Model: ATA ST9750420AS (scsi)
Disk /dev/sda: 750GB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt

Number  Start   End     Size    File system  Name                          Flags
 1      17,4kB  1049kB  1031kB               BIOS boot partition           bios_grub
 3      26,8GB  27,2GB  315MB   ntfs         Basic data partition          hidden, diag
 4      27,2GB  27,3GB  105MB   fat32        EFI system partition          boot
 5      27,3GB  27,4GB  134MB                Microsoft reserved partition  msftres
 6      27,4GB  299GB   272GB   ntfs         Basic data partition          msftdata
 7      327GB   721GB   394GB                Microsoft basic data          msftdata
 8      721GB   742GB   20,3GB  ext4         Linux filesystem
 9      742GB   750GB   8487MB  ext4         Linux filesystem

Ubuntu is installed on partition number 8, windows 8.1 on 6 (it created the 3,4 and 5 during the installation)

I tried boot-repair and I got some error messages.

• EFI detected. Please check the options
• EFI detected. Please use Boot-Repair-Disk-64-bit (www.sourceforge.net/p/boot-repair-cd) which contains an EFI-compatible version of this software.

Then I tried is boot-repair-disk (64-bit) on a pendrive, but it can't repair the boot. Here is the error message:

You have installed on sda8 a Linux version which is not EFI-compatible. It is probably incompatible with your computer. Please install an EFI-compatible system. For example, Linux-Secure-Remix-64bit and Ubuntu-64bit are EFI-compatible systems

Command os-prober gives nothing:

root@Clenet:/home/clenet# os-prober
root@Clenet:/home/clenet# 

Here is the output of update-grub.

root@Clenet:/home/clenet# update-grub
Generating grub.cfg ...
Found linux image: /boot/vmlinuz-3.12.0-031200-generic
Found initrd image: /boot/initrd.img-3.12.0-031200-generic
Found linux image: /boot/vmlinuz-3.11.0-15-generic
Found initrd image: /boot/initrd.img-3.11.0-15-generic
Found linux image: /boot/vmlinuz-3.8.0-35-generic
Found initrd image: /boot/initrd.img-3.8.0-35-generic
Found linux image: /boot/vmlinuz-3.12.0-031200-generic
Found initrd image: /boot/initrd.img-3.12.0-031200-generic
Found linux image: /boot/vmlinuz-3.11.0-15-generic
Found initrd image: /boot/initrd.img-3.11.0-15-generic
Found linux image: /boot/vmlinuz-3.8.0-35-generic
Found initrd image: /boot/initrd.img-3.8.0-35-generic
Found memtest86+ image: /boot/memtest86+.bin
done
root@Clenet:/home/clenet#