krfb server fails to start after upgrade fom 24.04 to 24.10

[pseco]

Yesterday upgraded successfully from kubuntu 24.04 to 24.10. Then immediately krfb stopped working. I launch krfb and the dialog shows as usual with Enable Desktop Sharing enabled, but if I untick it, then tick it again, shows the message:

Error — Desktop Sharing
Failed to start the krfb server. Desktop sharing will not work. Try setting another port in the settings and restart krfb.

Changing the port number and changing from xcb to qt doesn’t make any difference.

Any help? Looks like it’s a bug since was working perfectly fine in 24.04.

Changing to qt does not work:

krfb
QSocketNotifier: Can only be used with threads started with QThread
Wayland: Detected invalid configuration: preferredFrameBufferPlugin is not pipewire:  "qt"
QObject::connect(FrameBuffer, RfbServerManager): invalid nullptr parameter​

[pseco]

Nobody has this issue?

[drdata]

Nobody has this issue?

Yes! Just installed a new kubuntu 24.10 machine and got this problem. Have you tried changing settings to use screendump xcb instead of qt?

[pseco]

I've found out that KDE/Plasma is not yet compatible with Wayland, and some programs will not work:

$ krfb --help
QSocketNotifier: Can only be used with threads started with QThread

x11vnc -usepw -forever -display :0
Enter VNC password:
Verify password:
Write password to /home/kde/.vnc/passwd? [y]/n
Password written to: /home/kde/.vnc/passwd
21/11/2024 10:40:28 x11vnc version: 0.9.16 lastmod: 2019-01-05 pid: 18145
21/11/2024 10:40:28 Wayland display server detected.
21/11/2024 10:40:28 Wayland sessions are as of now only supported via -rawfb and the bundled deskshot utility. Exiting.

The way to fix it is to use another desktop:

• Plasma (Wayland): no remote desktop apps are working at least the ones I tried
• Plasma (X11): freezes when trying to enter to desktop in normal session
• Xubuntu Session: works fine

I selected Xubuntu Session and made it default in sddm.
After being logged in locally, go to Applications > Settings Manager > Session and Startup > Application Autostart > + Add > in command put "x11vnc --usepw -forever -display :0" > OK.
The command also works running it from the terminal.
Then after each login remote desktop over VNC is already running.

In Kubuntu 22.04 Krfb was running perfectly fine but in 22.10 Ubuntu switched to Wayland. The problem is that some software is not yet compatible, and probably won't be until 23.04 or even later.

So my advice is STAY ON UBUNTU 22.04 LTS until 26.04 LTS comes out to avoid weird issues. On Arch linux this does not happen.

[claydoh]

I've found out that KDE/Plasma is not yet compatible with Wayland,

That is patently not accurate
Plasma has a well supported Wayland implementation, and is the default session type for Plasma 6 --- X11 is still an available login session option, however, so x11vnc should still work there. I suspect opengl/graphics rendering may be as much a culprit here. iut has been an issue with VNC and similar protocols in the past.

On Arch linux this does not happen.

well, yeah, Arch has all the current up to date bits, and an Ubuntu LTS +1 doesn't.

[pseco]

I can't login with X11, get a black screen and only the mouse. I've gotta use Wayland.