Troubleshoot Dual Boot Loader issue Windows and Ubnuntu

Ubuntu or any other Linux distributions use the GRUB boot loader and Windows use NTLDR. if you are installing  Ubuntu after Windows  it may overwrite your MBR and  you won’t be able to boot into Windows.

In this post I will show you how to fix windows entry in Linux grub to get window menu in start-up.

I have used Windows 10 and Ubuntu 16.04

follow the Below steps:-

In Ubuntu run the below command

#sudo grub-mkconfig -o /boot/grub/grub.cfg

If your grub is grub2 like in CentOS7 and RHEL 7 then run the below one

#sudo grub2-mkconfig -o /boot/grub2/grub.cfg

you will see result as below. Now reboot the machine and check if your Windows is showing at startup.

IF above solution does not help you get back your Windows follow the below steps.  edit the file  /etc/grub.d/40_custom

#cd /etc/grub.d/

#vi  40_custom

# add following lines in 40_custom file:

menuentry "Windows 10" {

set root='(hd0,1)'

chainloader +1

}

And run the below

In Ubuntu run the following command

#sudo grub-mkconfig -o /boot/grub/grub.cfg

If your grub is grub2  CentOS7 and RHEL 7 then run the below one

#sudo grub2-mkconfig -o /boot/grub2/grub.cfg

Reboot the machine and check, you will see Windows 10 to start.