Full install Ubuntu 16.04 LTS SanDisk 32GB Ultra 3.0

[sudodus]

Welcome to the Ubuntu Forums

I have been thinking a lot about the things that you want to do, and I think I have a solution. I install bootloaders for both UEFI and BIOS mode, and for an external drive. You can do it yourself 'from scratch' according to the description or take a short-cut and use the compressed image files. It is described and explained at the following links,

Installation/UEFI-and-BIOS with details at .../stable-alternative

Portable installed system that boots in UEFI as well as in BIOS mode

Hi all,

I've read Sudodus' suggestions, but they seemed a bit more complicated than what I had time for, especially with taking out the hard drive, which is not very easy for my Acer V7-482PG laptop.

...

Thanks in advance!

Good luck trying along the advice of oldfred

But if still no luck, you can 'take a short-cut and use the compressed image files' according to my first post. You need not remove your internal drive to use that method.

[Doktertje]

Hi oldfred,

I did the following things after your latest piece of advice:

1) run sudo efibootmgr to find which entry is booted first. This was the ubuntu entry, because I had already previously set that ubuntu must be booted first in my BIOS. I ran your commands anyway, just to be sure;

2) I mounted /dev/sda2 on /mnt/efipart (my windows ESP partition) and copied the ubuntu folder from there to my home folder (easier to copy it to here first, then move it to its designated spot);

3) unmount /dev/sda2 from /mnt/efipart and mount /dev/sdb1 (USB ESP partition) on /mnt/efipart. I made the folder /EFI and copied the ubuntu folder into this folder. I made the Boot folder within /EFI and also copied the ubuntu folder into this Boot folder (/EFI/Boot). In the Boot folder, I renamed shimx64.efi to bootx64.efi;

4) I rebooted my laptop and booted into BIOS. I found an option to set "trust" on files (didn't know this option existed in my BIOS) and set trust on shimx64.efi, bootx64.efi, and grub.cfg (maybe the name of the grub file is wrong, but it was at least the grub file within the ubuntu folder). This added these files to "allowed databases";

5) I shutdown my laptop and booted again, with the USB drive with Ubuntu inserted. My laptop booted straight into Windows, even without showing GRUB.

My BIOS boots in UEFI mode, not Legacy mode.

Did I miss something here?
What commands can I run next to give you more information?

Kind Regards,

Sjoerd

[oldfred]

In the sdb drive it has to be /EFI/Boot/bootx64.efi.
Your description seems to say it is /EFI/Boot/ubuntu/bootx64.efi

And it has to be /EFI/ubuntu for the standard grub/ubuntu files.
The versions of shim & grub installed to sda normally are hard coded to look for /EFI/ubuntu.

The trust settings would normally be on the files in the internal drive.
The external drive should always boot from /EFI/Boot/bootx64.efi.