Complete Guide To Install Windows 10 With Ubuntu in Dual Boot [2021]

This guide will help you to install Windows 10 and Ubuntu as a dual boot in a system.

WARNING:
Before you proceed with the below instructions, make sure you have taken a backup and created recovery USB stick for Windows 10 because you may end up with a broken system. Also, you should know that below instructions are specific to a configuration (however, should work in most of the Laptop hardware) but the mileage may vary.

Installing Ubuntu and other Linux OS as dual boot is difficult in pre-installed Windows Laptops due to certain features and restrictions. Secure boot, fast boot, SATA AHCI modes – all these options make it a bit complicated to make a system dual boot with Windows 10 and Ubuntu, especially for the general users.

Here are the steps.

Prerequisite

Laptop with OEM installed Windows 10
One USB stick min 16GB for Windows 10 recovery
One USB stick with the latest bootable Ubuntu. To create an Ubuntu bootable stick, use Rufus. Follow below detailed instructions:
How to create Ubuntu bootable USB using Rufus in Windows

Backup and Recovery

Before you begin, make sure you take a backup of your personal data to a USB stick. Also for Windows 10 system files, create a recovery stick. Follow below instruction to create a recovery USB.

Insert an empty 16GB+ USB stick to Windows 10 machine
Open Control Panel
Search with ‘recovery’
Click on Create a recovery drive

Control Panel - Recovery — Control Panel – Recovery

Wait till the recovery is complete. Once completed, safely remove the USB stick from machine

To be on the safe side, you can check whether the recovery stick works via booting from it.

Create Partition for Ubuntu

If you have already a partition that you can use to install Ubuntu, you may want to skip this step.

OEM installed machines with Windows 10, typically comes with two basic partitions (excluding the recovery partitions). C:\ and D:\. C Drive contains Windows 10 system files and D Drive is reserved for user data. Ubuntu (18.04) needs a minimum of 25GB storage space partition which we need to create by shrinking C:\ drive which typically contains the majority of the space. Follow the below steps to create a partition for Linux.

Open partition editor from the START menu by searching ‘partition’.
Right-click on C Drive and click ‘Shrink Volume’.

In the next window, you can see the available size available in MB. Enter the value as per your need in MB in the ‘amount of space to shrink in MB’.
Tip: If you need 50 GB for partition – enter 50*1024= 51200 MB

Click ‘Shrink’ and wait it finishes.
You will see an unallocated space is created in a graphical display of your storage. This space would be used to install Ubuntu. Do not format now as Ubuntu installer would give you the option to format during installation.

Configure BIOS to change SATA to AHCI

If your system’s SATA controller mode is set to AHCI, you can skip this step. You can check it via entering into BIOS via function keys while booting up.

Ubuntu installer can not detect disk partitions if the SATA controller mode as SATA RAID IDE, or Intel RST. If you try to install Ubuntu in the above created partition with SATA controller mode as SATA RAID IDE or Intel RST, you would encounter below error: ‘You need at least 8.5 GB disk space to install Ubuntu.”.

Ubuntu Installer not able to detect storage

To change the SATA controller mode to AHCI, follow the below steps.

Open ‘cmd’ from the start menu as Administrator.
Run below command to turn on the safe mode in the next reboot.

bcdedit /set {current} safeboot minimal

If the above command doesn’t work, run below.

bcdedit /set safeboot minimal

Reboot the computer and press the respective key multiple times to enter into bios. Keys may vary for a different manufacturers. It should be either F2, F8.
In BIOS configuration settings change the SATA controller to AHCI.

You will get a warning as below. Press Yes.

Press F10 – save and exit.
After reboot, Windows 10 would boot into Safe Mode.
Open ‘cmd’ as Administrator again and run below commands.

bcdedit /deletevalue {current} safeboot

If the above command doesn’t work, run below.

bcdedit /deletevalue safeboot

Plugin the Ubuntu bootable USB now and reboot.

Install Ubuntu

Make sure BIOS settings set to boot from USB. Insert the Ubuntu USB stick and reboot.

If everything works well till now, the Ubuntu installer would start from a USB stick.
Continue to follow the on-screen instruction till the Installation Type window.
In the Installation Type window, choose ‘Something Else’.

In the partition list, select the partition which you have created in the first step. Then click Change. In the next window, select mount point as “/” and Type=ext4. Press ok.
Select the root device in the boot loader installer drop-down. DO NOT choose Windows Bootloader.

Press ok. And continue the installation and follow the instruction on screen.
After installation is complete, the installer would reboot the system. Remove the Ubuntu bootable USB stick before reboot.

You should be greeted with the GRUB with Windows boot loader and Ubuntu.

Choose your desired OS to proceed.

Conclusion

The above instructions are tested in Lenovo Ideapad Flex 5 series with OEM installed Windows 10. Drop a comment below if you are facing difficulties while dual-booting Windows 10 and Ubuntu.