[SOLVED] X11 "Cannot write display number to fd 9"

bunnycat · 2026-08-19 17:17:21

Hello forums.

I have been trying to use X11 and it doesn't appear to like me very much. I normally use KDE Plasma on Wayland, but after logging out and switching to KDE Plasma X11, it brings me to a black screen with a cursor that I cannot move. I believed this to be something related to just KDE Plasma and therefore didn't bother too much with it, but I tried moving to awesomewm today and had the same issue. Use Wayland, log out, log into awesomewm, black screen with a cursor I can't move. I have found very little posts with similar issues and I haven't quite found any solutions that would apply to me... similar posts seemed to have been posted in this subforum, however, so I will do the same.

Xorg.0.log - https://pastebin.com/5KLqdFq8

I do not believe I have a hybrid graphics set up, my fetch only brings up one GPU (it is marked as discrete). I start my sessions from SDDM.

Any help is greatly appreciated, I've been looking at moving to X11 for a little while now, but this keeps getting in my way.

Last edited by bunnycat (Yesterday 12:59:35)

Lone_Wolf · 2026-08-19 17:50:55

Please post the output of pacman -Qs xf86-video

Also the contents of your ~/.xinitrc .

bunnycat · 2026-08-19 18:44:36

pacman -Qs xf86-video

local/xf86-video-amdgpu 25.0.0-1 (xorg-drivers)
    X.org amdgpu video driver
local/xf86-video-ati 1:22.0.0-3 (xorg-drivers)
    X.org ati video driver
local/xf86-video-nouveau 1.0.18-1 (xorg-drivers)
    Open Source 3D acceleration driver for nVidia cards

I do not appear to have ~/.xinitrc as a file or directory...

Lone_Wolf · 2026-08-19 19:23:47

Remove all 3 of them, they are rarely needed nowadays.

for KDE plasma you'll need to install plasma-x11-session. Keep in mind that the next version of plasma 6.8 will remove support for X11 .

While X11 can be started through sddm (and most other display managers) starting it manually is often better, especially when troubleshooting .

Install xorg-server and xorg-xinit (first may already be installed)

For details on how to configure xinit/startx see https://wiki.archlinux.org/title/Xinit

seth · 2026-08-19 20:38:56

SDDM logs X11 into /var/log/X11, did you configure SDDM to use https://wiki.archlinux.org/title/SDDM#Wayland ?
I suspect the hand-off in the other direction works even less.

The error shows up after ~200s, apparently you were trying to switch the VT?
It's unrelated to your pointer issues but likely indicative of the same problem.

bunnycat · 2026-08-19 22:15:30

I have uninstalled all three of the xf86-video packages. I also already have plasma-x11-session, xorg-server, and xorg-xinit.
I don't have a /var/log/X11 folder.
I do not recall configuring SDDM at all, but upon further look, I believe it does use Wayland, or at least lacks root privileges. I couldn't find the folder specified (/etc/sddm.conf.d) but checking the owner of the kwin_wayland results in my username, which I think means it isn't elevated..?
I was not trying to switch VT, I can guarantee that.
When I get the chance, I will figure out how to start X11 manually and post again, I simply wanted to add what information I could before I forgot.

seth · 2026-08-19 22:19:39

checking the owner of the kwin_wayland results in my username, which I think means

… that you're running a KDE wayland session right now.

Exit your current session into SDDM, then actually do switch the VT (ctrl+alt+F3), login on the console and check the process list.

ps aux | grep -iE 'xorg|wayland'

bunnycat · 2026-08-19 23:59:14

Apologies for my mistake last time. I did the command, here are the results. It makes me believe that it is elevated but I am uncertain.

root       30173  0.0  0.0 107072 32484 ?        S    19:56   0:00 /usr/lib/plasmalogin-helper --socket /tmp/plasmalogin-auth-7d2eb7bb-2e20-40d4-a143-98ec8381f2cb --id 6 --start /usr/bin/startplasma-login-wayland --user plasmalogin --greeter
plasmal+   30213  0.1  0.1 201000 35892 tty1     Ssl+ 19:56   0:00 /usr/bin/startplasma-login-wayland
plasmal+   30235  5.3  0.8 1869088 294252 ?      Ssl  19:56   0:00 /usr/bin/kwin_wayland --no-lockscreen --no-global-shortcuts --no-kactivities --inputmethod plasma-keyboard --locale1
awolen     30569  0.0  0.0   6876  4328 tty3     S+   19:57   0:00 grep --color=auto -iE xorg|wayland

(still planning on doing the x11 thing, just can't right now, will update when i can ^^)

seth · 2026-08-20 00:18:32

You're not using SDDM but https://wiki.archlinux.org/title/Plasma_Login_Manager - which is a wayland process.
You could indeed try to replace that w/ SDDM to see whether it's holding onto your mouse.
In that case it could also be a specific issue w/ one of the devices of your input zoo

bunnycat · Yesterday 12:19:12

I replaced Plasma Login Manager with SDDM, which did work... sort of. All my sessions appear in the session drop down, but I can only pick Plasma Bigscreen. Not sure why and I can't look too closely right now, but any ideas as to why would be appreciated. I was able to pick Plasma (wayland) and other sessions before on Plasma Login Manager, so I don't think something is wrong with my session .desktop files..?

bunnycat · Yesterday 12:59:15

Good news, figured it out. Had more time than I thought I did, and it got X11 working! I was able to load into Plasma (X11) and awesomewm. I suppose the issue really was the Plasma Login Manager

Arch Linux

#1 2026-08-19 17:17:21

[SOLVED] X11 "Cannot write display number to fd 9"

#2 2026-08-19 17:50:55

Re: [SOLVED] X11 "Cannot write display number to fd 9"

#3 2026-08-19 18:44:36

Re: [SOLVED] X11 "Cannot write display number to fd 9"

#4 2026-08-19 19:23:47

Re: [SOLVED] X11 "Cannot write display number to fd 9"

#5 2026-08-19 20:38:56

Re: [SOLVED] X11 "Cannot write display number to fd 9"

#6 2026-08-19 22:15:30

Re: [SOLVED] X11 "Cannot write display number to fd 9"

#7 2026-08-19 22:19:39

Re: [SOLVED] X11 "Cannot write display number to fd 9"

#8 2026-08-19 23:59:14

Re: [SOLVED] X11 "Cannot write display number to fd 9"

#9 2026-08-20 00:18:32

Re: [SOLVED] X11 "Cannot write display number to fd 9"

#10 Yesterday 12:19:12

Re: [SOLVED] X11 "Cannot write display number to fd 9"

#11 Yesterday 12:59:15

Re: [SOLVED] X11 "Cannot write display number to fd 9"

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