boot Ubuntu 14.04.3 problem from grub2

Question

I have a problem installing Ubuntu 14.04 LTS on my ASUS Zenbook UX301LA-DH71T.

The long story:

I installed an older version of Ubuntu when I bought the Zenbook (I think it was a 12.XX version). I had a problem at some point and installed a new linux kernel. Ever since I've seen the occasional "system error" flag but things have worked fine, so I didn't update and just keep things as is.

Recently I decided to run an update and I lost all ability to connect to a network: wifi, ethernet, nothing worked. I tried the apt-get commands I found on Ubuntu forums for people who lost the wifi display but that obviously didn't help. So, I backed everything up and attempted to install 14.04.3 from my flash drive. I choose the option to install without internet connection, and then had some success getting the Ubuntu 14.04.3 LTS desktop to show up, with internet connections. I selected the "MIT" wifi. However, in attempting to complete the install, an error occurred when I had to pick a time zone. A field opened with question marks in it. So, I attempted to reinstall and hit "yes" to install with internet connection but the option no longer was available.

I went back to Ubuntu forums and decided to turn off boot security. Now when I turn the computer on it takes me straight to grub command line.

The current problem (short story):

How can I install Ubuntu 14.04.3 LTS from grub2 command line? Here is the info in the only directory I've been able to look around in:

grub> ls
(hd0) (hd0,gpt3) (hd0,gpt1) (hd0,gpt1)
grub> ls (hd0,1)/efi/ubuntu/
./ ../ shimx64.efi grubx64.efi grub.cfg MokManager.efi 

Any help / recommendations would be greatly appreciated!

Answer 1

Turning off Secure Boot was unnecessary in your case and is, generally speaking, inadvisable. If Secure Boot causes a problem, it will be a problem that causes Ubuntu to not boot at all -- you wouldn't even see a grub> prompt. The fact that you got into a desktop well before you disabled Secure Boot means that it's not the problem.

If you're seeing a grub> prompt, then that means that a mis-configured GRUB is booting. My hunch is that you're booting to an old GRUB installation that's trying to access a now-nonexistent Ubuntu partition. There are a couple of ways around this problem:

• Delete the old GRUB files -- Ubuntu installs GRUB to the EFI/ubuntu directory on the EFI System Partition (ESP). You can delete that directory, assuming you don't need to preserve that GRUB installation (as you certainly don't if you've deleted Ubuntu, or even if you intend to re-install it). Of course, deleting that directory will be a challenge if you can't get anything to boot; but if you know how to boot into another OS, or even an EFI shell, you should be able to delete it. Once it's gone, the EFI won't be able to launch this non-functional GRUB, and the firmware will instead move on to another boot options.
• Use the built-in boot manager to boot something else -- Most computers display a boot manager if you hit Esc, Enter, or a function key soon after powering on. (Which key does this varies greatly from one computer to another. Some machines display a prompt about this matter, but on some you may need to read the manual or just try keys randomly until something works.) Using this key, you should be able to select a boot option. With the Ubuntu install medium inserted, pick it -- and more specifically, pick the option that refers to the USB drive with the string "UEFI" attached to the description.

If you're having problems booting the Ubuntu installer, try creating it again. You may need to try with another program -- some programs for doing this job omit the EFI-mode boot loader or install it in a way that doesn't work with all EFI-based computers. Rufus and Unetbootin generally do a reasonable job of it, but I can't promise that either will work for you.