I have installed RHEL 7.2 alongside Windows 10. Windows 10 is already installed then RHEL is intalled properly and working fine. I have configured 40_custom file now Windows option is showing in boot time but on selecting Windows 10 it shows me the error:

An operating system was not found. Try disconnecting any drive that don't contain an operating system.

My /etc/grub/40_custom file entry is below

menuentry "windows 10" --class windows --class os {
insmod part_msdos
insmod ntfs
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root B4FC1483FC1441D2
chainloader +1

My blkid command show details as below

/dev/sda1: LABEL="SYSTEM_DRV" UUID="6010-8D9E" TYPE="vfat" PARTLABEL="EFI system partition" PARTUUID="bcba126d-db37-4ce3-8d7c-bbe60c532d01" 

/dev/sda2: PARTLABEL="Microsoft reserved partition" PARTUUID="50d92595-2f86-4524-b41d-f000a418942d" 

/dev/sda3: LABEL="Windows" UUID="B4FC1483FC1441D2" TYPE="ntfs" PARTLABEL="Basic data partition" PARTUUID="68463e8d-ee49-46ae-9aed-f73a4745ed09" 

/dev/sda4: LABEL="LENOVO" UUID="462E5C292E5C13F1" TYPE="ntfs" PARTLABEL="Basic data partition" PARTUUID="c7d64ac1-eb24-4f2b-8641-71505a0272df" 

/dev/sda5: LABEL="WINRE_DRV" UUID="FCDA1684DA163B7A" TYPE="ntfs" PARTLABEL="Basic data partition" PARTUUID="819bc20d-bf85-4108-bc68-77bdf2bb587e" 

/dev/sda6: PARTUUID="6d39590b-c929-4be2-a70d-bcdd2f5a2466" 

/dev/sda7: UUID="36923994-c0b2-4611-9296-ecbc5aca194a" TYPE="xfs" PARTUUID="59b6c4e4-d481-44e1-a9f8-61ae77b87c59" 

/dev/sda8: UUID="cwCIH2-v4lZ-aRAD-y4iy-5BVE-cxdW-4bESf5" TYPE="LVM2_member" PARTUUID="44880cbc-4c41-424d-9c14-a9a57ff7ab76" 

/dev/mapper/rhel-root: UUID="e742b9d8-09ae-42de-bfbf-2a38db682764" TYPE="xfs" 

/dev/mapper/rhel-swap: UUID="abebad3e-00bb-416e-8420-8495b8d3564d" TYPE="swap" 

My fdisk -l command showing following details:

WARNING: fdisk GPT support is currently new, and therefore in an experimental phase. Use at your own discretion.

Disk /dev/sda: 2000.4 GB, 2000398934016 bytes, 3907029168 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
Disk label type: gpt

#         Start          End    Size  Type            Name
 1         2048       534527    260M  EFI System      EFI system partition

 2       534528       567295     16M  Microsoft reser Microsoft reserved partition

 3       567296   3642836991    1.7T  Microsoft basic Basic data partition

 4   3852552192   3904980991     25G  Microsoft basic Basic data partition

 5   3904980992   3907028991   1000M  Windows recover Basic data partition

 6   3642836992   3642841087      2M  BIOS boot parti 

 7   3642841088   3643621375    381M  Microsoft basic 

 8   3643621376   3852552191   99.6G  Linux LVM       

Disk /dev/mapper/rhel-root: 99.0 GB, 98968797184 bytes, 193298432 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

Disk /dev/mapper/rhel-swap: 8002 MB, 8002732032 bytes, 15630336 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

You seem to have somehow booted and installed RHEL using legacy boot. This won't work, as your existing OS uses UEFI boot; you'll need to reinstall RHEL booting with UEFI.

  • But i had made the bootable USB for RHEL, which is showing only when i enable Legacy. In UEFI mode i am not able to boot with USB.
    – sujeet
    Jan 14 '19 at 11:52
  • How did you make the USB stick? Jan 14 '19 at 15:34
  • using iso2usb software i make the bootable usb. But if i install RHEL using UEFI mode then my windows will back or not..?
    – sujeet
    Jan 15 '19 at 12:31
  • If you install RHEL with UEFI, you will be able to booth both operating systems. Jan 15 '19 at 15:25
  • thanks a lot , you saved me, i installed RHEL in UEFI mode and now able to boot into both OS.
    – sujeet
    Jan 15 '19 at 16:12

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