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I was using windows 10 installed on a SSD plus an HHD for storage. Recently, I have added another ssd where I have installed Ubuntu 18.04.2 LTS

My problem is that neither os-prober nor grub can find windows 10. However, I am able to boot in windows 10 from the UEFI boot menu. I read all the posts about it but could not solve the problem. Can you please help me?

Here is the output from boot info Boot Info Script 0.61 [1 April 2012]

============================= Boot Info Summary: ===============================

=> Windows is installed in the MBR of /dev/sda. => Windows is installed in the MBR of /dev/sdb. => Windows is installed in the MBR of /dev/sdc.

sda1: __________________________________________________________________________

File system:       ntfs
Boot sector type:  Windows Vista/7: NTFS
Boot sector info:  No errors found in the Boot Parameter Block.
Operating System:  
Boot files:        /bootmgr /Boot/BCD /Windows/System32/winload.exe

sda2: __________________________________________________________________________

File system:       ntfs
Boot sector type:  Windows Vista/7: NTFS
Boot sector info:  No errors found in the Boot Parameter Block.
Operating System:  
Boot files:        

sdb1: __________________________________________________________________________

File system:       
Boot sector type:  -
Boot sector info: 
Mounting failed:   mount: /tmp/BootInfo-OmyD6Lmf/sdb1: unknown filesystem type ''.

sdb2: __________________________________________________________________________

File system:       ntfs
Boot sector type:  Windows Vista/7: NTFS
Boot sector info:  No errors found in the Boot Parameter Block.
Operating System:  
Boot files:        

sdc1: __________________________________________________________________________

File system:       vfat
Boot sector type:  FAT32
Boot sector info:  No errors found in the Boot Parameter Block.
Operating System:  
Boot files:        /efi/BOOT/fbx64.efi /efi/ubuntu/fwupx64.efi 
                   /efi/ubuntu/grubx64.efi /efi/ubuntu/mmx64.efi 
                   /efi/ubuntu/shimx64.efi

sdc2: __________________________________________________________________________

File system:       ext4
Boot sector type:  -
Boot sector info: 
Operating System:  Ubuntu 18.04.2 LTS
Boot files:        /boot/grub/grub.cfg /etc/fstab

============================ Drive/Partition Info: =============================

Drive: sda _____________________________________________________________________ Disk /dev/sda: 111,8 GiB, 120034123776 bytes, 234441648 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos

Partition Boot Start Sector End Sector # of Sectors Id System

/dev/sda1 * 2,048 233,517,055 233,515,008 7 NTFS / exFAT / HPFS /dev/sda2 233,517,056 234,438,655 921,600 27 Hidden NTFS (Recovery Environment)

Drive: sdb _____________________________________________________________________ Disk /dev/sdb: 931,5 GiB, 1000204886016 bytes, 1953525168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disklabel type: gpt

Partition Boot Start Sector End Sector # of Sectors Id System

/dev/sdb1 1 4,294,967,295 4,294,967,295 ee GPT

/dev/sdb1 ends after the last sector of /dev/sdb

GUID Partition Table detected.

Partition Start Sector End Sector # of Sectors System /dev/sdb1 34 262,177 262,144 Microsoft Reserved Partition (Windows) /dev/sdb2 264,192 1,953,523,711 1,953,259,520 Data partition (Windows/Linux)

Drive: sdc _____________________________________________________________________ Disk /dev/sdc: 223,6 GiB, 240057409536 bytes, 468862128 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: gpt

Partition Boot Start Sector End Sector # of Sectors Id System

/dev/sdc1 1 468,862,127 468,862,127 ee GPT

GUID Partition Table detected.

Partition Start Sector End Sector # of Sectors System /dev/sdc1 2,048 1,050,623 1,048,576 EFI System partition /dev/sdc2 1,050,624 468,860,927 467,810,304 Data partition (Linux)

"blkid" output: ________________________________________________________________

Device UUID TYPE LABEL

/dev/loop0 squashfs
/dev/loop1 squashfs
/dev/loop10 squashfs
/dev/loop11 squashfs
/dev/loop12 squashfs
/dev/loop13 squashfs
/dev/loop14 squashfs
/dev/loop15 squashfs
/dev/loop16 squashfs
/dev/loop17 squashfs
/dev/loop2 squashfs
/dev/loop3 squashfs
/dev/loop4 squashfs
/dev/loop5 squashfs
/dev/loop6 squashfs
/dev/loop7 squashfs
/dev/loop8 squashfs
/dev/loop9 squashfs
/dev/sda1 6EAEC608AEC5C933 ntfs Fisso /dev/sda2 34D8E21FD8E1DEDC ntfs
/dev/sdb1
/dev/sdb2 1688449A884479EF ntfs Fisso exp /dev/sdc1 3BCC-705C vfat
/dev/sdc2 b64bdc97-1ec9-4a7f-a4f6-7e0e51b54f2d ext4

================================ Mount points: =================================

Device Mount_Point Type Options

/dev/sdc1 /boot/efi vfat (rw,relatime,fmask=0077,dmask=0077,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro) /dev/sdc2 / ext4 (rw,relatime,errors=remount-ro)

=========================== sdc2/boot/grub/grub.cfg: ===========================

  • 1
    Windows is in legacy mode, so to run it from grub, you would need to boot grub in legacy mode, but you installed it in UEFI mode. Easiest just to reinstall Ubuntu in legacy mode. How you boot the install media (legacy vs. UEFI) is how it installs. – ubfan1 Mar 25 at 21:06
  • Many thanks for your answer. I will try to convert my Ubuntu installation from UEFI to legacy. Can I ask you how did you understand that Windows was not in UEFI? – wminnella Mar 26 at 8:02
1

Windows is in legacy mode, so to run it from grub, you would need to boot grub in legacy mode, but you installed it in UEFI mode. Easiest just to reinstall Ubuntu in legacy mode. How you boot the install media (legacy vs. UEFI) is how it installs

Your Windows 10 installation is on a dos partitioned (vs gpt) disk, so that alone implies a legacy installation. Its disk also has an MBR boot setup, and no EFI partition, so those are other clues it's a legacy install. Ubuntu works in either mode (legacy/UEFI) on any disk partition type (dos/gpt), but usually for UEFI uses the more more modern gpt, but its disk (sdc) does have an EFI partition with the Ubunu bootloaders, so a UEFI install was done. If you want a legacy install on that disk, you will need to either:

  1. Add a grub-bios 2M unformatted partition (since grub cannot tuck it's code between the partitions on a gpt disk) or
  2. Repartition the disk using a DOS partition table (no grub-bios partition needed in this case).
  • The gpt partitioning has some advantages over the old MBR, so I would suggest to keep gpt, add bios_grub partition anywhere on drive, and use Boot-Repair in BIOS boot mode of Ubuntu installer to install grub to sdc. Do not use auto fix as that installs grub to MBR of every drive & you want to keep Windows boot loader on MBR of sda. Use advanced mode and choose install & drive for grub. Grub only boots working Windows, so sometimes you may need to directly boot Windows to make repairs. – oldfred Mar 26 at 15:46

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