GRUB does not detect Windows

Question

I have finally installed Ubuntu on my second drive. When I start my computer GRUB only offers me to boot Ubuntu, not Windows 7. What needs to be done so that I can choose between Ubuntu and Windows in GRUB?

When I press F12 for boot menu at startup and I choose Windows Boot Manager it boots into Windows 7.

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I ran command sudo fdisk -l and here is log (http://pastebin.com/Cgv1igHc):

WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted.


Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 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
Disk identifier: 0xc3ffc3ff

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1  1953525167   976762583+  ee  GPT
Partition 1 does not start on physical sector boundary.

Answer 1

I had issues like here above and the solution was just to add manual entry as below:

menuentry "WINDOWS10 (on /dev/sda1)" --class windows --class os { insmod part_msdos insmod ntfs set root='(/dev/sda,msdos1)' search --no-floppy --fs-uuid --set=root 688EB92384B85968 drivemap -s (hd0) ${root} chainloader +1 }

where UUID above (688E...) was taken from boot windows disk via blkid /dev/sdb1

ATTENTION:additionally line: set root='(/dev/sda,msdos1)' refers to sda which is visible under ubuntu as /dev/sdb even actually it is the first disk in sata bus while /dev/sda is in fact second drive mounted as root / Maybe that is why grub scripts could not work properly. I had no time to change the physical order of disks but it is quite possible it would help to resolve the issue, too. Best Regards Luke

Answer 2

I had the same problem with Windows 10. I installed Linux Mint 18.1 Cinnamon 64-bit on my laptop for dual boot with WIN10. After the installation GRUB only offered to boot Linux but not Windows. I found this video https://www.youtube.com/watch?v=0fCA7ToywoY and this article https://forums.linuxmint.com/viewtopic.php?f=46&t=209082, but unfortunately both didn't work for me so I use a combination of these two to resolve my problem.

Open your terminal and follow these commands and open the file named 40_custom:

sudo gedit /etc/grub.d/40_custom

Add these lines to the file and then save and exit.

menuentry "Windows 10" {

   set root='{hd0,1}'

   chainloader + 1

}

After you save the file update your GRUB with this line:

sudo update-grub

Then restart your machine to see if it works.

Hope this will work for others too.

Answer 3

I had the same problem and had spent 2 days figuring it out. But today I had this sudden idea in the morning and it worked out.

You should review your bios/uefi settings. In my case I had to let Uefi boot first. Otherwise I wasn't able to detect windows from ubuntu. What I had to set was ubuntu > Windows Boot Manager > DISK1 > DISK2 > DISK3. Insted DISK1 > ubuntu > Windows Boot Manager > DISK3.

I had 2 ubuntu installations one on hdd and one on ssd. Apparently ssd installation wasn't showing as UEFI for some reasone but I wanted boot faster disk first.

I wasn't expecting that order of boot can influence grub in detecting systems. So it is worth to review that.

Answer 4

If you have previously had a RAID installed that may be causing issues. In my case, I built my desktop in 2010, and I installed two 1.5 TB with a striped RAID. User gracemercy54 mentions here that this is left over metadata from the former RAID configuration.

When I originally tried the steps by Hermes I got an error specifying "wrong number of devices in a RAID set." So, if this happens to you open a terminal and run:

   sudo dmraid -rE
   sudo os-prober
   sudo update-grub

That fixed this for me.

Answer 5

I had Windows 10 running and then tried dual boot. Once Ubuntu was installed, Win 10 wasn't showing up in my GRUB loader. I tried the following --

First of all, I disabled Secure Boot in Win10. Then ran the below commands in Ubuntu :

sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install -y boot-repair && boot-repair

Worked out pretty well. Was able to find both Windows and Ubuntu in GRUB after that.

Answer 6

I solved a similar problem following steps of Boot-Repair

Install boot-repair

sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install -y boot-repair && boot-repair

Push "Recommended repair" And put in a terminal some commands as it suggested.

I think my Grub doesn't recognize windows due to a bad shutdown, and it solved the problem.

Answer 7

If the os-prober method above doesn't work try to add a custom grub menu entry

documented here edit the /etc/grub.d/40_custom file

menuentry "Windows 7" {  
     insmod ntfs  
     set root='(hd0,1)'  
     search --no-floppy --fs-uuid --set a3f1ea41fc67a3f1  
     chainloader +1  
}

to get the uuid you can to use the blkid /dev/sdx command

Answer 8

1. Boot Ubuntu and mount your Windows partition (simply open the disk on Nautilus)

2. Run the following on the command line (Ctrl+Alt+t):

   sudo os-prober
   

3. If your Windows installation was found, you can run:

   sudo update-grub
   

Note that step 2 is just for your convenience. You could just mount the Windows 7 partition and then run update-grub.

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