[SOLVED] Ubuntu 20.04 vm boots into black screen on Proxmox VE 8.1

R3dPanda

New Member
Apr 8, 2024
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Hello dear proxmox community,

i'm currently trying to set up a ubuntu 20.04 (mini iso) vm.
So far i was able to create a new vm, install ubuntu 20.04 and boot into the os (default display settings). For further configuration i'm downloading and executing a script that installs various additional packages and configures auto-login after boot. As soon as i reboot the vm after the script ran trough successfully i do however get booted to a black screen from which i can't seem to recover.

So far i have tried the following to fix this issue:
1. Checking if the vm boots successfully
The vm still seems to boot fine and gets an ipaddress assigned that i can ping and ssh into it.

2. Changing display settings
Trough playing around with the display settings i found out that i can successfully boot to the desktop of the vm if i change them to 'vmware compatible'. This however seems to be the only option that is currently working. Neither the 'default' setting (despite working pre-script) nor 'Spice' seems to work as they both directly boot me to the black screen.

3. Setting fixed display memory

While researching a bit i found a couple of threads that hinted to a problem with configuring auto-login and automatic window resizing on a ubuntu vm. The fix suggested (setting a fixed number of memory for display -> 24MiB) did however not resolve the problem.

4. Checking missing packages
I checked and installed the packages 'qemu-guest-agent' and 'spice-vdagent'. This however did also not resolve the issue.

As i am still pretty enw to proxmox ve i would relly appeciate any help/input that helps to resolve my issue or hints me in the right direction.

Kind regards
R3dPanda
 
Through more research i have found the culprit.

For future people visiting this thread: There is a know bug in ubuntu 19.X - 20.X with the splash screen breaking the auto-login
https://ubuntuhandbook.org/index.ph...n-enabled-in-ubuntu-19-10-with-nvidia-driver/

You can simply fix this by editing the file /etc/default/grub inside the vm:
Code:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
Simply remove the 'splash' keyword and save the file.

Afterwards regenerate grub with the following command and reboot the machine:
Code:
update-grub
 
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