Got my Dell XPS 9560 replaced by warranty after motherboard on previous one went bad. Took out the HDD on the new unit and swapped it out with SSD in previous unit. In the past when swapping out hard drives, if the computer didn't boot to grub, I'd just boot to Ubuntu Live USB and run boot-repair. It would detect all OSes and repair grub, etc. This time however it only detected the Ubuntu partition on the SSD, not the Windows partition. os-prober returns nothing. I can mount and read and write to Windows partition just fine from Ubuntu. Since I've simply used boot-repair in the past I'm pretty unfamiliar with EFI, grub, boot flags/required partitions, etc. Here is output from fdisk -l:

Device          Start        End   Sectors   Size Type
/dev/sdb1        2048      34815     32768    16M Microsoft reserved
/dev/sdb2       34816  748181142 748146327 356.8G Microsoft basic data
/dev/sdb3   748181504  749150207    968704   473M Windows recovery environment
/dev/sdb4   749152256  750200831   1048576   512M EFI System
/dev/sdb5   750200832 1448673279 698472448 333.1G Linux filesystem
/dev/sdb6  1448673280 1465147391  16474112   7.9G Linux swap
/dev/sdb7   749150208  749152255      2048     1M BIOS boot

Partition table entries are not in disk order.
  • You can use windows iso to repair the windows boot manager Commented Dec 22, 2017 at 22:08

2 Answers 2


Forget os-prober, add static grub entry /etc/grub/40_custom .

menuentry 'Windows 10' -class windows {
    search --fs-uuid --no-floppy --set=root XXXX-XXX
    chainloader (${root})/EFI/Microsoft/Boot/bootmgfw.efi

Replace XXXX-XXXX with UUID (not PARTUUID) found from blkid /dev/sdb4 (EFI System)


Try one of the following :

  1. From a live-cd run "sudo dd if=/usr/lib/syslinux/mbr/mbr.bin of=/dev/sdb
  2. Run form Microsoft Windows iso image, "lets say Windows 7" go to the rapir and get into the CMD and run this command. x:\source\bootrec /fixboot

Regards, Mahmood Shehab

  • 3
    This is a UEFI system. The master boot record is not relevant anymore. Commented Sep 27, 2019 at 19:11

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