Ubuntu 18.04 fails to boot even in recovery mode (stuck on loading initial ram disk) on ASUS UX433FA

So I had a working dual boot set up with Ubuntu 18.04 and Windows 10, when I ran an apt upgrade and now I can no longer boot into Ubuntu (windows works fine), with the recovery mode output stuck at “Loading initial ramdisk”. Previously, I’ve noted that my laptop is unable to run Ubuntu 19.04 (but it is able to run 18.10), with it also resulting in the same problem of being stuck on “loading initial ramdisk”.

I ran the yannubuntu boot repair tool, which fixed the problem for exactly one boot - without any apt upgrades or installations, the laptop failed to boot on successive attempts. Boot repair doesn’t work on further attempts either, here is the pastebin from the output: http://paste.ubuntu.com/p/wkGfGdQgJH/

This laptop model has no discrete graphics card so it’s not a driver issue with that.

Running the Linux 5.1.1 kernel, and switching to an older kernel does not help either

Solved by following this: Ubuntu 18.04.2 boot stuck on purple screen after updates

The issue was due to an intel microcode update, which behaved badly with ASUS laptops. In short, the fix (for now) is to first add dis_ucode_ldr to the kernel command line. Do this by pressing E while on the grub boot menu and find the line which has something like “ro quiet splash”. Add dis_ucode_ldr at the end of the line. This will let you boot.

Once you boot, run

sudo apt install intel-microcode=3.20180312.0~ubuntu18.04.1

This undoes the problematic update in question and will allow you to boot from now on out (without having to modify grub).

I have had the same issue after installing updates from apt-get on a Dell Latitude 7400 running Ubuntu 18.04. Booting stopped after GRUB - can just see a blank purple screen. No luck with recovery mode either which gets stuck at Loading initial ramdisk

I tried installing different kernels using the method in this answer which essentially drops to the root level of the existing Ubuntu installation after mounting the existing installation in a live usb session (Try Ubuntu without installing option). All the kernels got stuck at the same point after GRUB - just a blank purple screen. Recovery modes get stuck at Loading initial ramdisk

What helped was editing the kernel command by pressing e (as soon as you press e the full blown kernel command will show up) when the GRUB menu/screen (the purple screen with options like Ubuntu, Advanced Ubuntu options, System settings etc.) showed up and adding the microcode dis_ucode_ldr at the end of the (kernel) line that has ro quiet splash (the line appears towards the end of the kernel command)

Once the microcode is added to the line, the boot will succeed and once logged in, I executed the command

sudo apt install intel-microcode=3.20180312.0~ubuntu18.04.1

to avoid having to add the microcode to the kernel command in GRUB during every reboot.

Other things that helped me were a deeper understanding of the boot process outlined here (power button -> BIOS -> POST -> MBR -> bootloader (GRUB) -> GRUB loads linux kernel etc.)