Dualboot Ubuntu/Windows: "Error: file '/EFI/Microsoft/Boot/bootmgfw.efi' not found"

It is work for me.

1. Create a bootable windows 10 USB.
2. Select USB from boot menu.
3. "Repair your computer" > Troubleshoot > Startup Repair.
4. Done

It take few seconds. :)

I had the same problem as Tayfe(top most post), suddenly when ever i selected windows 10 from the grub boot menu this error popped up "error: file '/EFI/Microsoft/Boot/bootmgfw.efi' not found".

I tried editing the grub.cfg file as mentioned above but it did not help.

The efi file was there when i browsed to the location using file explorer its just that during booting it was not being found.

What i did to fix it was (first from boot menu disabled secure boot)(edited)

1.Created a bootable windows 10 usb

1a.downloaded the windows 10 iso from windows official website.

1b.Used balenaEtcher(this is the only rufus alternative i found for ubuntu) to create a bootable windows 10 media.

  1b1.First format the usb.

  1b2.Then using Gparted(in device tab in Gparted) create a new partition table (type of partition == GPT ).

  1b3.then created a new partition of fat32 type(allocated all the space to this partition so there is only a single partition on the usb)

1bc.Used balena etcher to etch the windows 10 iso file onto this usb(it gave a warning regarding the iso that it might not get recognised ignore it(i did)).

2.Now once u have a bootable windows 10 usb, restart the pc and when u are in the grub boot menu press c to enter the command line.

3.Press ls.

4.It will show all the harddrives on the pc.

5.My usb was (hd0) (yours may appear different but u can find it by first doing the "ls" part without having the usb inserted then again with the usb inserted) or like in the next step

6.to see the detail about a harddisk (eg for the (hd0) do "ls (hd0)" it will show you the details , i knew this is my bootable usb by comparing the size and also the name, eg for (hd1,msdos) run "ls (hd1,msdos)" like this).

7.Now run "set root=(hd0)" your "(hd0)" part may be diff.

8.now run "ls -l /"

9.this will show all the files on the root which is the usb now

10.if there is a "efi" DIR then everything is fine and u can follow along.

11.now just check "ls -l /efi/boot/" has an efi file or not mine showed me a file bootx64.efi when i ran this command.

12.You can also make sure your path "/efi/boot/bootx64.efi" is a correct path by opening the usb in ubuntu first and going to this path from the file explorer to check everything

13.So after the run root=(hd0) command, run this command "chainloader /efi/boot/bootx64.efi"

14.then if the command ran okay, run "boot".

15.this will boot into windows 10 installation, follow this link (https://www.thewindowsclub.com/boot-or-repair-windows-10-using-the-installation-media) from step number 3 or the instructions below

15a When you boot from the USB drive, it will kickstart Windows 10 installation. Do not have a craving to keep hitting next, or you will end up installing Windows. On the first installation screen, look for a link “Repair your computer.” Click on it. It will boot your computer into Advanced Recovery.

15b When at the advanced troubleshooting, select Advanced Options. Select Troubleshoot. Under Advanced options screen, you will see Startup Repair. Click on it and follow the instructions.

16.I followed all this and my error was fixed, hope the same happens for you.

I'm not sure whats the exact way to solve this problem. But I tried a few thing and finally came up with a solution! So at least a small summarize:

At some point I felt like I had completely messed up the UEFI. When booting the laptop mouse and keyboard were flashing once before they turned them self off again just before even GRUB or UEFI could be loaded. And when trying to boot from a USB stick I also got stuck with a blank screen. So I decided to simply reset the UEFI to factory standards. This solved the problems with mouse, keyboard and USB stick!

To solve the actual problem

error: file '/EFI/Microsoft/Boot/bootmgfw.efi' not found

I decided to give it a try and edit /boot/grub/grub.cfg as mentioned in my first post. I changed just this one single line, nothing else! This made it working for me! So now I can boot into Ubuntu and Windows 10 again from GRUB. The only thing I'm actually wondering about is where I got this file at /EFI_PRE_RESCATUX_2020-09-01-20-46-59/Microsoft/Boot/bootmgfw.efi from. Yes it looks a lot like Rescatux is responsible for this but I don't know exactly what I did that rescatux created this backup file.

Good luck if you're facing a similar problem! :)