Fresh install of 18.10 stuck at initializing ramdisk after sudo apt upgrade

[Sam]

**Specs**
- Asus Zenbook 14 UX433FN (NVMe PCIe SSD)
- Ubuntu 18.10 and Windows 10 dual boot, Windows 10 working fine.

**Background**
After successful FRESH install of Ubuntu 18.10 desktop using LiveUSB, and subsequent update using either command prompt (sudo apt upgrade) or via the GUI that appears after first reboot (security updates etc.)

**How to reproduce the bug**
1. Fresh (minimal) install of Ubuntu 18.10
2. Reboot successfully.
3. Either:
  3a. Open terminal and run
  $ sudo apt upgrade
  3b. Wait for Ubuntu to automatically show the GUI prompt asking for installation of important updates (eg. security)
4. Update successful
5. Reboot
6. Boot stuck at `Loading initial ramdisk...`, even in recovery mode.

**Suspected problem**
Broken package. Note that minimal installation is used.

More information in the AskUbuntu Forum: https://askubuntu.com/questions/1144688/ubuntu-18-10-stuck-at-initialising-ramdisk-after-fresh-install-and-subsequent-up

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[tylef (tylef)]

Same problem with my Asus UX480F with Ubuntu 18.04 or 19.10. Majority of boot doesn't work stuck with "Loading initial ramdisk" but sometimes boot is completed, it's very strange.

Other people have this type of bug (https://askubuntu.com/questions/1144800/ubuntu-18-04-2-boot-stuck-on-purple-screen-after-updates).

Disable secureboot, fastboot, add nomodeset doesn't work.

Boot seems work every time with acpi=off.

[Chris Seeley (sealy-au)]

ASUS UX433 dmesg output from a boot that made it to cmd line
http://sealy.hypnos.feralhosting.com/dmesg.log

[Chris Seeley (sealy-au)]

also, this may relate to https://bugs.launchpad.net/ubuntu/+source/linux-signed-hwe/+bug/1829784

[Mark (markthecodehamster)]

Possible duplicate of https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1829620
where we found the culpit (intel-microcode) and have a workaround.

[jarglim (milgraj)]

I had the same exact problem with my installation. It occurred that the solution was quite simple. Please update the bios in UX433FN to version 306 or newer (this is the one that helped me). After this update, everything should start to work without any problems.

[Alexis Trinquet (vynix)]

I ran into the same issue on a fresh install of 18.04. Before downloading the updates I could boot just fine but now I always get stuck on a purple screen.

However there is a catch, my system uses a AMD CPU (Athlon II X2 245)

If I boot into recovery mode, a bunch of text passes by (so fast that I can't read it) before getting stuck on [SDG] Attached SCSI disk

[Grashdur (grashdur)]

I've got the same problem, but it's on a virtual machine. Is it possible to update BIOS on a virtual machine? I've been running 18.04 just fine for the past year and a half. But now installing 19.04 on VirtualBox, I get this permanent purple screen before reaching the login screen.