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I used a live USB to install Ubuntu on a second 128gb San Disk USB. However, when i open the boot menu of my PC, it displays this: Boot menu of my PC

It displays my boot devices. 1) Windows (SSD), 2) Ubuntu (SSD), 3) USB (Which is supposed to be Ubuntu)

When I try to boot from USB, it brings me right back to the boot menu, however, when I boot from the Ubuntu-labeled SSD, it boots like it is supposed to.

When I remove the USB, the Ubuntu-labeled ssd still shows up, but when I try to boot from it, it brings up a GRUB command prompt and does not boot Ubuntu.

Finally, the USB does not boot in any other PC.

Can someone please help me out?

C.J. DuHamel
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  • How did you partition the 128GB USB when you installed Ubuntu on it? – Smooth Researcher Jan 15 '20 at 06:09
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    UEFI only boots external devices from an ESP with /EFI/Boot/bootx64.efi. Ubuntu's Ubiquity only installs grub to first drive it sees usually sda or first NVMe drive. If you want UEFI boot you will need an ESP on the external drive.Ubuntu Installer uses wrong bootloader location for USB/sdb UEFI installs https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1173457 Posted work around to manually unmount & mount correct ESP during install https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1396379 – oldfred Jan 15 '20 at 15:29

1 Answers1

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The reason is that the bootloader is in the SSD.

The option to select drive (at the bottom of the 'Something else' partitioning window of the Ubuntu installer) works only in BIOS mode. In UEFI mode you must unplug, disconnect or disable the internal drive in order to write the bootloader (the EFI system partition) into the USB drive.

It is always a good idea to unplug, disconnect or disable the internal drive before you install Ubuntu into an external drive. This way you can be sure that the bootloader will be written where you want it, in the external drive.

The following link may help you make things work the way you want,

How do I install Ubuntu to a USB key? (without using Startup Disk Creator)

sudodus
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