Ubuntu 22.04 noVNC console black screen

S

Stik

Member
Aug 25, 2021
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Hello, one of you VMs have black screen instead of virtual console. Happily, it has ssh, and we can use this VM, but network configuration is problematic etc.


1730454206822.png

VM config:
Bash: 
# qm config 123
agent: 1
balloon: 0
boot: order=scsi0;ide2;net0
cores: 8
cpu: host
ide2: none,media=cdrom
memory: 262144
meta: creation-qemu=7.2.0,ctime=1688023397
name: jupyter4
net0: virtio=***,bridge=vmbr0,firewall=1,tag=***
numa: 0
onboot: 1
ostype: l26
scsi0: data_203:123/vm-123-disk-0.qcow2,discard=on,iothread=1,size=500G,ssd=1
scsihw: virtio-scsi-single
smbios1: uuid=***
sockets: 2
vmgenid: ***

I've tried to change graphic card (varios variants) and this solution - nothing helps.
 
This problem persists with ubuntu 24.04

I found that if I restart the gdm after rebooting (via an ssh terminal), the noVNC window shows the desktop:

systemctl restart gdm

I've added this to be crontab as follows and will test to see if it works reliably, but whats causing it ?
 
https://askubuntu.com/questions/1526994/ubuntu-22-04-boots-to-black-screen-with-blinking-line - looks like this is same problem

Btw, restarting doesn't help:
Code: 
jupyter@jupyter4:~$ sudo systemctl status gdm                                                                                                       
● gdm.service - GNOME Display Manager                                                                                                               
     Loaded: loaded (/lib/systemd/system/gdm.service; static)                                                                                       
     Active: active (running) since Tue 2025-09-02 18:14:12 MSK; 1min 1s ago                                                                       
    Process: 70281 ExecStartPre=/usr/share/gdm/generate-config (code=exited, status=0/SUCCESS)                                                     
   Main PID: 70286 (gdm3)                                                                                                                           
      Tasks: 3 (limit: 309198)                                                                                                                     
     Memory: 1.4M                                                                                                                                   
        CPU: 129ms                                                                                                                                 
     CGroup: /system.slice/gdm.service                                                                                                             
             └─70286 /usr/sbin/gdm3                                                                                                                 
                                                                                                                                                    
сен 02 18:14:23 jupyter4 gdm3[70286]: Gdm: GdmDisplay: Session never registered, failing                                                           
сен 02 18:14:23 jupyter4 gdm3[70286]: Gdm: Child process -70398 was already dead.                                                                   
сен 02 18:14:23 jupyter4 gdm-launch-environment][70402]: pam_unix(gdm-launch-environment:session): session opened for user gdm(uid=127) by (uid=0) 
сен 02 18:14:23 jupyter4 gdm-launch-environment][70402]: pam_unix(gdm-launch-environment:session): session closed for user gdm                     
сен 02 18:14:23 jupyter4 gdm3[70286]: Gdm: GdmDisplay: Session never registered, failing                                                           
сен 02 18:14:23 jupyter4 gdm-launch-environment][70402]: GLib-GObject: g_object_unref: assertion 'G_IS_OBJECT (object)' failed                     
сен 02 18:14:23 jupyter4 gdm3[70286]: Gdm: GdmLocalDisplayFactory: maximum number of X display failures reached: check X server log for errors     
сен 02 18:14:23 jupyter4 gdm3[70286]: Gdm: Child process -70407 was already dead.                                                                   
сен 02 18:14:23 jupyter4 gdm3[70286]: Gdm: GdmDisplay: Session never registered, failing                                                           
сен 02 18:14:23 jupyter4 gdm3[70286]: Gdm: Child process -70407 was already dead.

And this helps:
Code: 
sudo apt-get install --reinstall ubuntu-desktop
sudo systemctl restart gdm 
sudo systemctl status gdm 
● gdm.service - GNOME Display Manager                                                                                                             
     Loaded: loaded (/lib/systemd/system/gdm.service; static)                                                                                     
     Active: active (running) since Tue 2025-09-02 18:28:37 MSK; 4s ago                                                                           
    Process: 627778 ExecStartPre=/usr/share/gdm/generate-config (code=exited, status=0/SUCCESS)                                                   
   Main PID: 627785 (gdm3)                                                                                                                        
      Tasks: 4 (limit: 618827)                                                                                                                    
     Memory: 4.6M                                                                                                                                 
        CPU: 54ms                                                                                                                                 
     CGroup: /system.slice/gdm.service                                                                                                            
             └─627785 /usr/sbin/gdm3                                                                                                              
                                                                                                                                                  
сен 02 18:28:37 jupyter5 systemd[1]: Starting GNOME Display Manager...                                                                            
сен 02 18:28:37 jupyter5 systemd[1]: Started GNOME Display Manager.                                                                               
сен 02 18:28:37 jupyter5 gdm-launch-environment][627789]: pam_unix(gdm-launch-environment:session): session opened for user gdm(uid=127) by (uid=0)
 
Last edited:
My issue is not quite the same. I get a black screen, and the cursor is a white cross that I can move around the screen. I've tested restarting gdm, which did then restore my desktop, but sometimes not on the first try.
 
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