I tried to install Ubuntu on a different partition on my laptop and it worked but i cant boot windows anymore.

I tried boot-repair automated solution but that didn't help, and Grub Customizer doesn't show my windows.

Here is the boot repair info script if anyone can figure out what i can do, thank you!


  • It looks like you converted UEFI install of Ubuntu to BIOS/MBR boot. Windows only boots from MBR with BIOS and only from gpt with UEFI. But I do not think you can easily convert to gpt and have Windows work. Windows 10 is not dual boot friendly in the old BIOS/MBR boot mode as it turns fast start up on with updates. And then you have to temporarily reinstall a Windows boot loader, fix Windows and then restore grub to MBR. In UEFI mode, you can just directly boot Windows from UEFI. Fast start up off: askubuntu.com/questions/843153/… – oldfred Mar 3 at 20:35

Your laptop has a UEFI BIOS which is being run in legacy mode. It looks like it's now being run in full UEFI mode, or at least Ubuntu is booting up with grub using an ESP (EFI System Partition) it made on installation. Windows is now reliant on that ESP to boot. But your disk is formatted as an MBR (dos disk) and with Windows installed on such disks it cannot boot from an ESP or work in UEFI mode. Read this.

Ideally you should convert your disk from MBR to GPT. Windows will then be recognised and work in UEFI mode and boot from the ESP, although you may still need to do another LU boot-repair. Normally you lose everything on that disk on GPT conversion as it is wiped. But there is software that can perform this task for free without loss of data (so they claim). But you need to boot to Windows to download and run it. As it now seems the Windows System partition has been altered by Grub to an ESP you won't be able to do that directly without further work to restore the original Windows Boot Manager files, destroying the grub efi files as well. You can do this by booting Windows from a flash drive if you already have one, (or download W10 ISO in Ubuntu and make one and test it) then use its repair option. If this doesn't work the best route is back up your data, and start from scratch, re-installing W10, changing your BIOS to UEFI mode first before you start. Windows will convert your disk to GPT during installation.

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