Cannot boot off of USB Flash Drive to Install Ubuntu

Question

UNetBootin tells me to reboot after it's done placing the contents on my flash drive.

After I restart my PC, I press the DEL key to enter the BIOS. I then go to the Boot Menu and change the 1st Boot Priority to the Removable Media (Sometimes it shows up as USB:2.0).

After that, I press F10 to save the changes and it restarts my PC. I see the American Megatrends Boot Screen and then my Hardware Monitor, but I never see a purple screen come up, instead I get the Windows boot screen with the starting Windows caption.

What have I missed?

Answer 1

This Answer is assuming that your laptop is using UEFI. UEFI is the replacement for BIOS. Which provides an abstraction between Operating System and Hardware and is used to boot up your Computer. Every new computer ships with UEFI as default.

A Bit of Theory

When booting up your computer the EFI System searches the active drives that are connected to your Computer for an executable in the folder /EFI/BOOT. If such an executable is found the drive is considered to be bootable.

The BIOS on the other assumed that your boot manager is stored in the first section of the hard drive.

What's Happening

UNetBootin configures your USB Stick in the old MBR Style. (Which is that the first section contains the boot manager). Your UEFInow searches the USB Stick for the /EFI/BOOT/BOOTx64.EFI (or similar) executable and obviously can't find it so it continues, according to the boot order to search the next defined device until it finds one which contains said executable. This is why you can't boot from your USB Stick.

Fixing the Issue

There are two ways to fix your issue.

1: In order to keep compatibility legacy mode has been built into most EFI Systems which allow to boot from an MBR Partitioned drive. In order to activate legacy mode you will first have to disable Secure Boot because that will prevent you from Activating legacy mode and then you will have to activate legacy mode. These Settings can be found in your UEFI Boot Configuration (or BIOS) under System Configuration and or Security.

2: Nowadays most Linux Systems support UEFI Boot. To make sure open your ISO (for Example with Virtual Clone Drive and check that the folder /boot/efi exists. If it does all you have to do is to format your drive to FAT32 and extract the content of the ISO into the root folder of the USB Stick (Copy Paste from Mounted Image or extract with WinRar). note: you still have to disable Secure Boot

I hope my answer has shed some light onto the issue.

Answer 2

Did your computer come with Windows 8 or Macintosh installed, if so you have the UEFI BIOS setup. To get it to boot of of the flash-drive you will need to disable secure boot, Intel SRT, and FastStartup. After that you should be able to boot to the drive.

Stop here if that worked, keep reading if you still can't boot into the flash-drive.

If you still cannot boot to the drive you should try to change the boot mode, there are normally only two options, UEFI and legacy (legacy might be CSM Boot like in the example below). If you have any more questions or it still won't work let us know. I am certan everyone here is more than happy to help!

Answer 3

I had this issue when trying to install Ubuntu 20.04 on a laptop that wasn't automatically recognizing the flash device as a boot option.

In the BIOS settings, under Boot Configuration, click add a new boot option to UEFI (not legacy boot). When a flash drive is plugged in, the middle value will be autofilled. Leave that. Choose any name and select the [. . .] button to open the ubuntu boot medium filesystem.

Navigate to /EFI/BOOT/ and select GRUBx64.EFI. Make sure the checkbox beside the new option is checked. Now applying the settings, exiting, and smashing f12 to get to the boot options menu should let you choose that option you made.

This did not work for me when selecting /EFI/BOOT/BOOTx64.EFI, but it is worth a shot for anyone reading this.

@spitterfly helped point me in the right direction.