Unable to boot Windows 8 after Ubuntu installation

Unable to boot Windows 8 after Ubuntu installation

I installed Ubuntu on a pc with Windows 8 preinstalled.
After installation Grub showed Ubuntu entries and Windows 8 Boot Manager
(or something similar), selecting it I got:
/EndEntire
file path
/ACPI(a0341d0,0)/PCI(2,1f)/UnknownMessaging(12)/HD(2,e1800,82000,963b540a6178e211,8d,38)/File(\EFI\Microsoft\Boot)/File(bootmgfw.efi)/EndEntire
error: cannot load image.
After that I run boot-repair with the default options.
This is the file it generated: http://paste.ubuntu.com/6005571
And this grub entries:
Ubuntu
Advanced options for Ubuntu
Windows UEFI bkpbootmgfw.efi
Windows Boot UEFI loader
EFI/toshiba/Boot/bootmgfw.efi
Windows Boot Manager (UEFI on /dev/sda2)
System setup (Bios menu)
The four about Windows 8 all give a similar error message:
Windows UEFI bkpbootmgfw.efi
/EndEntire file path
/ACPI(a0341d0,0)/PCI(2,1f)/UnknownMessaging(12)/HD(2,e1800,82000,963b540a6178e211,8d,38)/File(\EFI\Microsoft\Boot)/File(bootmgfw.efi)/EndEntire
error: cannot load image.
Windows Boot UEFI loader
/EndEntire file path
/ACPI(a0341d0,0)/PCI(2,1f)/UnknownMessaging(12)/HD(2,e1800,82000,963b540a6178e211,8d,38)/File(\EFI\Microsoft\Boot)/File(bkpbootx64.efi)/EndEntire
error: cannot load image.
EFI/toshiba/Boot/bootmgfw.efi
/EndEntire file path
/ACPI(a0341d0,0)/PCI(2,1f)/UnknownMessaging(12)/HD(2,e1800,82000,963b540a6178e211,8d,38)/File(\EFI\toshiba\Boot)/File(bootmgfw.efi)/EndEntire
error: cannot load image.
Windows Boot Manager (UEFI on /dev/sda2)
/EndEntire file path
/ACPI(a0341d0,0)/PCI(2,1f)/UnknownMessaging(12)/HD(2,e1800,82000,963b540a6178e211,8d,38)/File(\EFI\Microsoft\Boot)/File(bootmgfw.efi)/EndEntire
error: cannot load image.
How can I fix this?