Starting Fedora 40 KDE X11 session immediately crashes system

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Love wayland, but I have a use case or two that makes me prefer X11 for now.

I did a fresh Fedora 40 install as soon as it released, installed the plasma-workspace-x11 package through dnfso I could select it from SDDM, and everytime I try to do so, I get an instant system crash. It appears to kick me into TTY2 first, then completely freeze the whole system.

My journalctl logs don’t seem to provide much info:

Jun 07 01:04:44 melinoe uresourced[1728]: Setting resources on user-1000.slice (MemoryMin: 0, MemoryLow: 0, CPUWeight: 100, IOWeight: 100)
Jun 07 01:04:44 melinoe uresourced[1728]: Setting resources on user@1000.service (MemoryMin: 0, MemoryLow: 0, CPUWeight: 100, IOWeight: 100)
Jun 07 01:04:44 melinoe uresourced[1728]: Setting resources on user-988.slice (MemoryMin: 262144000, MemoryLow: 0, CPUWeight: 500, IOWeight: 500)
Jun 07 01:04:44 melinoe uresourced[1728]: Setting resources on user@988.service (MemoryMin: 0, MemoryLow: 0, CPUWeight: 100, IOWeight: 100)
Jun 07 01:04:44 melinoe wireplumber[1942]: spa.bluez5.midi: org.bluez.GattManager1.RegisterApplication() failed: GDBus.Error:org.bluez.Error.AlreadyExists: Already Exists
Jun 07 01:04:44 melinoe bluetoothd[1141]: Endpoint registered: sender=:1.56 path=/MediaEndpoint/A2DPSource/ldac
Jun 07 01:04:44 melinoe bluetoothd[1141]: Endpoint registered: sender=:1.56 path=/MediaEndpoint/A2DPSink/aac
Jun 07 01:04:44 melinoe bluetoothd[1141]: Endpoint registered: sender=:1.56 path=/MediaEndpoint/A2DPSource/aac
Jun 07 01:04:44 melinoe bluetoothd[1141]: Endpoint registered: sender=:1.56 path=/MediaEndpoint/A2DPSink/sbc
Jun 07 01:04:44 melinoe bluetoothd[1141]: Endpoint registered: sender=:1.56 path=/MediaEndpoint/A2DPSource/sbc
Jun 07 01:04:44 melinoe bluetoothd[1141]: Endpoint registered: sender=:1.56 path=/MediaEndpoint/A2DPSink/sbc_xq
Jun 07 01:04:44 melinoe bluetoothd[1141]: Endpoint registered: sender=:1.56 path=/MediaEndpoint/A2DPSource/sbc_xq
Jun 07 01:04:44 melinoe bluetoothd[1141]: Endpoint registered: sender=:1.56 path=/MediaEndpoint/A2DPSource/faststream
Jun 07 01:04:44 melinoe bluetoothd[1141]: Endpoint registered: sender=:1.56 path=/MediaEndpoint/A2DPSource/faststream_duplex
Jun 07 01:04:44 melinoe bluetoothd[1141]: Endpoint registered: sender=:1.56 path=/MediaEndpoint/A2DPSink/opus_05
Jun 07 01:04:44 melinoe bluetoothd[1141]: Endpoint registered: sender=:1.56 path=/MediaEndpoint/A2DPSource/opus_05
Jun 07 01:04:44 melinoe bluetoothd[1141]: Endpoint registered: sender=:1.56 path=/MediaEndpoint/A2DPSink/opus_05_duplex
Jun 07 01:04:44 melinoe bluetoothd[1141]: Endpoint registered: sender=:1.56 path=/MediaEndpoint/A2DPSource/opus_05_duplex
Jun 07 01:04:48 melinoe sddm-greeter-qt6[1843]: file:///usr/share/sddm/themes/breeze/Main.qml:241:17 Parameter "username" is not declared. Injection of parameters into signal handlers is deprecated. Use JavaScrip>
Jun 07 01:04:48 melinoe sddm-helper[2277]: Detected locale "C" with character encoding "ANSI_X3.4-1968", which is not UTF-8.
                                           Qt depends on a UTF-8 locale, and has switched to "C.UTF-8" instead.
                                           If this causes problems, reconfigure your locale. See the locale(1) manual
                                           for more information.
Jun 07 01:04:48 melinoe sddm-helper[2277]: gkr-pam: unable to locate daemon control file
Jun 07 01:04:48 melinoe sddm-helper[2277]: gkr-pam: stashed password to try later in open session
Jun 07 01:04:48 melinoe sddm-helper[2277]: pam_kwallet5(sddm:auth): pam_kwallet5: pam_sm_authenticate
Jun 07 01:04:48 melinoe audit[2277]: USER_AUTH pid=2277 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:xdm_t:s0-s0:c0.c1023 msg='op=PAM:authentication grantors=pam_unix,pam_gnome_keyring acct="gabe" >
Jun 07 01:04:48 melinoe audit[2277]: USER_ACCT pid=2277 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:xdm_t:s0-s0:c0.c1023 msg='op=PAM:accounting grantors=pam_unix acct="gabe" exe="/usr/libexec/sddm>
Jun 07 01:04:48 melinoe sddm-helper[2277]: pam_kwallet5(sddm:setcred): pam_kwallet5: pam_sm_setcred
Jun 07 01:04:48 melinoe audit[2277]: CRED_ACQ pid=2277 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:xdm_t:s0-s0:c0.c1023 msg='op=PAM:setcred grantors=pam_unix,pam_gnome_keyring acct="gabe" exe="/us>
Jun 07 01:04:48 melinoe audit[2277]: USER_ROLE_CHANGE pid=2277 uid=0 auid=1000 ses=4 subj=system_u:system_r:xdm_t:s0-s0:c0.c1023 msg='op=pam_selinux default-context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0>
Jun 07 01:04:48 melinoe systemd-logind[1154]: New session 4 of user gabe.
Jun 07 01:04:48 melinoe systemd[1]: Started session-4.scope - Session 4 of User gabe.
Jun 07 01:04:48 melinoe sddm-helper[2277]: pam_unix(sddm:session): session opened for user gabe(uid=1000) by gabe(uid=0)
Jun 07 01:04:49 melinoe sddm-helper[2277]: gkr-pam: gnome-keyring-daemon started properly and unlocked keyring
Jun 07 01:04:49 melinoe sddm-helper[2277]: pam_kwallet5(sddm:session): pam_kwallet5: pam_sm_open_session
Jun 07 01:04:49 melinoe sddm-greeter-qt6[1843]: eglSwapBuffers failed with 0x300d, surface: 0x0
Jun 07 01:04:49 melinoe audit[2277]: USER_START pid=2277 uid=0 auid=1000 ses=4 subj=system_u:system_r:xdm_t:s0-s0:c0.c1023 msg='op=PAM:session_open grantors=pam_selinux,pam_loginuid,pam_selinux,pam_keyinit,pam_na>
Jun 07 01:04:49 melinoe sddm-helper[2277]: Starting X11 session: "/usr/bin/X -nolisten tcp -background none -seat seat0 -noreset -keeptty -novtswitch -verbose 3" "/etc/X11/xinit/Xsession \"/usr/bin/startplasma-x1>
Jun 07 01:04:49 melinoe bluetoothd[1141]: Endpoint unregistered: sender=:1.56 path=/MediaEndpoint/A2DPSource/ldac
Jun 07 01:04:49 melinoe bluetoothd[1141]: Endpoint unregistered: sender=:1.56 path=/MediaEndpoint/A2DPSink/aac
Jun 07 01:04:49 melinoe bluetoothd[1141]: Endpoint unregistered: sender=:1.56 path=/MediaEndpoint/A2DPSource/aac
Jun 07 01:04:49 melinoe bluetoothd[1141]: Endpoint unregistered: sender=:1.56 path=/MediaEndpoint/A2DPSink/sbc
Jun 07 01:04:49 melinoe bluetoothd[1141]: Endpoint unregistered: sender=:1.56 path=/MediaEndpoint/A2DPSource/sbc
Jun 07 01:04:49 melinoe bluetoothd[1141]: Endpoint unregistered: sender=:1.56 path=/MediaEndpoint/A2DPSink/sbc_xq
Jun 07 01:04:49 melinoe bluetoothd[1141]: Endpoint unregistered: sender=:1.56 path=/MediaEndpoint/A2DPSource/sbc_xq
Jun 07 01:04:49 melinoe bluetoothd[1141]: Endpoint unregistered: sender=:1.56 path=/MediaEndpoint/A2DPSource/faststream
Jun 07 01:04:49 melinoe bluetoothd[1141]: Endpoint unregistered: sender=:1.56 path=/MediaEndpoint/A2DPSource/faststream_duplex
Jun 07 01:04:49 melinoe bluetoothd[1141]: Endpoint unregistered: sender=:1.56 path=/MediaEndpoint/A2DPSink/opus_05
Jun 07 01:04:49 melinoe bluetoothd[1141]: Endpoint unregistered: sender=:1.56 path=/MediaEndpoint/A2DPSource/opus_05
Jun 07 01:04:49 melinoe bluetoothd[1141]: Endpoint unregistered: sender=:1.56 path=/MediaEndpoint/A2DPSink/opus_05_duplex
Jun 07 01:04:49 melinoe bluetoothd[1141]: Endpoint unregistered: sender=:1.56 path=/MediaEndpoint/A2DPSource/opus_05_duplex
Jun 07 01:04:49 melinoe sddm-helper-start-wayland[1817]: Stopping... "kwin_wayland"
Jun 07 01:04:49 melinoe sddm-helper-start-wayland[1817]: "QtDBus: cannot relay signals from parent QObject(0x563dd95f8110 \"\") unless they are emitted in the object's thread QThread(0x563dd94bc998 \"libinput-con>
Jun 07 01:04:49 melinoe sddm-helper[1725]: pam_unix(sddm-greeter:session): session closed for user sddm
Jun 07 01:04:49 melinoe audit[1725]: USER_END pid=1725 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:xdm_t:s0-s0:c0.c1023 msg='op=PAM:session_close grantors=pam_unix,pam_systemd acct="sddm" exe="/us>
Jun 07 01:04:49 melinoe audit[1725]: CRED_DISP pid=1725 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:xdm_t:s0-s0:c0.c1023 msg='op=PAM:setcred grantors=pam_permit acct="sddm" exe="/usr/libexec/sddm->
Jun 07 01:04:49 melinoe systemd[1]: session-c1.scope: Deactivated successfully.
Jun 07 01:04:49 melinoe systemd[1]: session-c1.scope: Consumed 2.962s CPU time.
Jun 07 01:04:49 melinoe systemd-logind[1154]: Session c1 logged out. Waiting for processes to exit.
Jun 07 01:04:49 melinoe systemd-logind[1154]: Removed session c1.
Jun 07 01:04:49 melinoe uresourced[1728]: Setting resources on user-988.slice (MemoryMin: 0, MemoryLow: 0, CPUWeight: 100, IOWeight: 100)
Jun 07 01:04:49 melinoe uresourced[1728]: Setting resources on user@988.service (MemoryMin: 0, MemoryLow: 0, CPUWeight: 100, IOWeight: 100)
Jun 07 01:04:49 melinoe uresourced[1728]: Setting resources on user-1000.slice (MemoryMin: 262144000, MemoryLow: 0, CPUWeight: 500, IOWeight: 500)
Jun 07 01:04:49 melinoe uresourced[1728]: Setting resources on user@1000.service (MemoryMin: 0, MemoryLow: 0, CPUWeight: 100, IOWeight: 100)
Jun 07 01:04:59 melinoe systemd[1]: Stopping user@988.service - User Manager for UID 988...

Weirdly, I see reference to kwin_wayland in my logs. But I’m certain from the timestamps that this is when I tried to launch the X11 session from SDDM.

Any further troubleshooting or guidance here?

This problem can also be seen coming from some reddit users.

My system:

Operating System: Fedora Linux 40
KDE Plasma Version: 6.0.5
KDE Frameworks Version: 6.2.0
Qt Version: 6.7.1
Kernel Version: 6.8.11-300.fc40.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 5700X 8-Core Processor
Memory: 31.2 GiB of RAM
Graphics Processor: AMD Radeon RX 6700 XT
Manufacturer: ASUS

Removed gnome, wayland, wireplumber

Did you install kwin-x11? It seems that KDE Plasma X11 is trying to launch the Wayland version of kwin.

Source that I referenced: Reddit

Yes, I had kwin-x11 installed as well during my initial troubleshooting. It didn’t change the outcome

Figured out a solution, thanks to Fedora 40 Kde Spin X11 doesn't exist - #15 by random0

I used sudo dnf in sddm-x11 --allowerasing to replace the wayland SDDM with the X11 SDDM. I guess the wayland-based SDDM just can’t deal with launching into X11. I’m not sure how anyone else got this working without following this step.

All well, everything works as expected now.