I just logged in in Debian  Trixie LXQt from LightDM and it works fine. Go figure.

I just checked out my Thinkpad which runs Gnome with LightDM and it works fine.

Well we know its crashing

123.697] (EE) [ 123.697] (EE) Backtrace: [ 123.709] (EE) unw_get_proc_name failed: no unwind info found [-10] [ 123.710] (EE) 0: /usr/lib/Xorg (?+0x0) [0x55a590d68514] [ 123.713] (EE) unw_get_proc_name failed: no unwind info found [-10] [ 123.714] (EE) 1: /usr/lib/libc.so.6 (?+0x0) [0x7f9e6bc57ef0] [ 123.716] (EE) 2: /usr/lib/libpciaccess.so.0 (pci_device_vgaarb_set_target+0x10f) [0x7f9e6c0d1f3f] [ 123.717] (EE) unw_get_proc_name failed: no unwind info found [-10] [ 123.718] (EE) 3: /usr/lib/Xorg (?+0x0) [0x55a590d7b903] [ 123.719] (EE) unw_get_proc_name failed: no unwind info found [-10] [ 123.719] (EE) 4: /usr/lib/Xorg (?+0x0) [0x55a590cf13f5] [ 123.720] (EE) 5: /usr/lib/Xorg (CloseDownExtensions+0x49) [0x55a590c93619] [ 123.722] (EE) unw_get_proc_name failed: no unwind info found [-10] [ 123.722] (EE) 6: /usr/lib/Xorg (?+0x0) [0x55a590c3ad66] [ 123.724] (EE) unw_get_proc_name failed: no unwind info found [-10] [ 123.725] (EE) 7: /usr/lib/libc.so.6 (?+0x0) [0x7f9e6bc416b5] [ 123.727] (EE) 8: /usr/lib/libc.so.6 (__libc_start_main+0x89) [0x7f9e6bc41769] [ 123.728] (EE) 9: /usr/lib/Xorg (_start+0x25) [0x55a590c3bcd5] [ 123.729] (EE) [ 123.729] (EE) Segmentation fault at address 0x30 [ 123.729] (EE) Fatal server error: [ 123.730] (EE) Caught signal 11 (Segmentation fault). Server aborting [ 123.730] (EE) [ 123.730] (EE) Please consult the The X.Org Foundation support at http://wiki.x.org for help. [ 123.730] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information. [ 123.731] (EE) This is from Xorg.0.log

Process 450 (Xorg) of user 0 dumped core. Stack trace of thread 450: #0 0x00007f68fa3dbf3f pci_device_vgaarb_set_target (libpciaccess.so.0> #1 0x000056114a5baf36 ddxGiveUp (/usr/lib/Xorg + 0x184f36) #2 0x000056114a5a247c FatalError (/usr/lib/Xorg + 0x16c47c) #3 0x000056114a597573 n/a (/usr/lib/Xorg + 0x161573) #4 0x00007f68f9f61ef0 n/a (libc.so.6 + 0x3def0) #5 0x00007f68fa3dbf3f pci_device_vgaarb_set_target (libpciaccess.so.0> #6 0x000056114a5aa903 n/a (/usr/lib/Xorg + 0x174903) #7 0x000056114a5203f5 n/a (/usr/lib/Xorg + 0xea3f5) #8 0x000056114a52143d n/a (/usr/lib/Xorg + 0xeb43d) #9 0x000056114a46a6f4 n/a (/usr/lib/Xorg + 0x346f4) #10 0x00007f68f9f4b6b5 n/a (libc.so.6 + 0x276b5) #11 0x00007f68f9f4b769 __libc_start_main (libc.so.6 + 0x27769) #12 0x000056114a46acd5 _start (/usr/lib/Xorg + 0x34cd5) Stack trace of thread 691: #0 0x00007f68f9fc1e22 n/a (libc.so.6 + 0x9de22) #1 0x00007f68f9fb5fda n/a (libc.so.6 + 0x91fda) #2 0x00007f68f9fb6024 n/a (libc.so.6 + 0x92024) #3 0x00007f68fa03d475 epoll_wait (libc.so.6 + 0x119475) #4 0x000056114a594c6e n/a (/usr/lib/Xorg + 0x15ec6e) #5 0x000056114a596459 n/a (/usr/lib/Xorg + 0x160459) #6 0x00007f68f9fb97eb n/a (libc.so.6 + 0x957eb) #7 0x00007f68fa03d18c n/a (libc.so.6 + 0x11918c) ELF object binary architecture: AMD x86-64 Here is partial code from my journalctl -U lightdm.service. It's too wide to copy it all.