"I was unable to sign into my KDE Plasma session until I downgraded JUST: # pacman -U /var/cache/pacman/pkg/xdg-desktop-portal-kde-5.27.8-1-x86_64.pkg.tar.zst"

This sounds extremely weird on many levels. Please try upgrading and downgrading again to be 100% sure that this is the cause.

Still reproducible on my system with both -2 and -3.

Unsure if this is related: After reverting back to -1, my screens end up backwards. I have to switch the side by side layout of the screens, I had to do this last night as well.


This morning I pacman -Syu (actually it was yay -Syu but no AUR packages).
:: 8 packages to upgrade/install.
8 core/btrfs-progs 6.5.1-1 -> 6.5.2-1
7 core/glibc 2.38-6 -> 2.38-7
6 core/hwdata 0.374-1 -> 0.375-1
5 core/lib32-glibc 2.38-6 -> 2.38-7
4 extra/pugixml 1.13-1 -> 1.14-1
3 extra/python-fastjsonschema 2.18.0-1 -> 2.18.1-1
2 extra/python-hypothesis 6.87.0-1 -> 6.87.1-1
1 extra/xdg-desktop-portal-kde 5.27.8-1 -> 5.27.8-3

Followed by

pacman -U /var/cache/pacman/pkg/xdg-desktop-portal-kde-5.27.8-2-x86_64.pkg.tar.zst

Then a reboot to re-test 5.27.8-2 first. Then I was testing both the newer 5.27.8-3 and 5.27.8-2, before I had to revert back to -1 to log in.

During the reboot I double checked the BIOS menus. At some point I must have reset to 'optimized defaults', and while overclocking was disabled in the overview menus there was a like 3-4 menu page deep option that was easy to overlook. Thank's Intel and ASUS for hiding "Turbo Mode" (not even clearly overclock) under Advanced \ CPU Configuration \ CPU Power Management Configuration > [Turbo Mode] . . .




grep segfault Tests?.txt
Tests2.txt:Oct 04 10:33:58 hostname kernel: kglobalaccel5[1957]: segfault at 29f557f193fd ip 00007f68db10d957 sp 00007ffc55194590 error 4 in libQt5XcbQpa.so.5.15.10[7f68db100000+9a000] likely on CPU 5 (core 1, socket 0)
Tests2.txt:Oct 04 10:33:58 hostname kernel: xdg-desktop-por[1929]: segfault at 29059030f11d ip 00007f38bd313957 sp 00007ffc1aaa3d80 error 4 in libQt5XcbQpa.so.5.15.10[7f38bd306000+9a000] likely on CPU 4 (core 0, socket 0)
Tests2.txt:Oct 04 10:33:58 hostname kernel: kalendarac[1928]: segfault at 328 ip 00007fc3ec2bf957 sp 00007ffd310ea4d0 error 4 in libQt5XcbQpa.so.5.15.10[7fc3ec2b2000+9a000] likely on CPU 2 (core 2, socket 0)
Tests2.txt:Oct 04 10:33:59 hostname kernel: kglobalaccel5[1995]: segfault at 299fe6a7839d ip 00007fe5a990d957 sp 00007ffd8879bfe0 error 4 in libQt5XcbQpa.so.5.15.10[7fe5a9900000+9a000] likely on CPU 2 (core 2, socket 0)
Tests2.txt:Oct 04 10:33:59 hostname kernel: kglobalaccel5[2045]: segfault at 293a2f58639d ip 00007f55be90d957 sp 00007ffd92dee3e0 error 4 in libQt5XcbQpa.so.5.15.10[7f55be900000+9a000] likely on CPU 3 (core 3, socket 0)
.
Tests3.txt:Oct 04 10:36:00 hostname kernel: xdg-desktop-por[2746]: segfault at 298c2d27e23d ip 00007f48b230d957 sp 00007ffe7d8dc200 error 4 in libQt5XcbQpa.so.5.15.10[7f48b2300000+9a000] likely on CPU 1 (core 1, socket 0)
Tests3.txt:Oct 04 10:36:01 hostname kernel: dde-widgets[2679]: segfault at 8 ip 00007f3679b66ae4 sp 00007ffcf874a5e0 error 4 in libstartup-notification-1.so.0.0.0[7f3679b66000+4000] likely on CPU 5 (core 1, socket 0)
.
Tests4.txt:Oct 04 10:43:12 hostname kernel: xdg-desktop-por[2678]: segfault at 29397227323d ip 00007f339010d957 sp 00007fffc0193590 error 4 in libQt5XcbQpa.so.5.15.10[7f3390100000+9a000] likely on CPU 7 (core 3, socket 0)
.
Tests4.txt:Oct 04 10:53:42 hostname kernel: xdg-desktop-por[4852]: segfault at 29cae1ec212d ip 00007f8e66b27957 sp 00007ffe642da300 error 4 in libQt5XcbQpa.so.5.15.10[7f8e66b1a000+9a000] likely on CPU 4 (core 0, socket 0)



Oct 04 10:33:58 hostname xdg-desktop-portal-kde[1929]: qt.qpa.xcb: could not connect to display :0
Oct 04 10:33:58 hostname kalendarac[1928]: qt.qpa.xcb: could not connect to display :0
Oct 04 10:33:58 hostname kglobalaccel5[1957]: qt.qpa.xcb: could not connect to display :0
Oct 04 10:33:58 hostname kernel: kglobalaccel5[1957]: segfault at 29f557f193fd ip 00007f68db10d957 sp 00007ffc55194590 error 4 in libQt5XcbQpa.so.5.15.10[7f68db100000+9a000] likely on CPU 5 (core 1, socket 0)
Oct 04 10:33:58 hostname kernel: Code: ff 74 0a 48 8b 07 ff 50 20 48 8b 43 20 48 85 c0 0f 84 4d 02 00 00 48 8b 43 08 48 63 50 08 48 8b 44 d0 10 48 8d 15 99 fb ff ff <48> 8b a8 08 03 00 00 48 8b 05 9b fd 0e 00 48 8b 38 48 8b 07 48 8b
Oct 04 10:33:58 hostname systemd[1]: Created slice Slice /system/systemd-coredump.
-- Subject: A start job for unit system-systemd\x2dcoredump.slice has finished successfully
-- Defined-By: systemd
-- Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- A start job for unit system-systemd\x2dcoredump.slice has finished successfully.
--
-- The job identifier is 1832.
Oct 04 10:33:58 hostname kernel: xdg-desktop-por[1929]: segfault at 29059030f11d ip 00007f38bd313957 sp 00007ffc1aaa3d80 error 4 in libQt5XcbQpa.so.5.15.10[7f38bd306000+9a000] likely on CPU 4 (core 0, socket 0)
Oct 04 10:33:58 hostname kernel: Code: ff 74 0a 48 8b 07 ff 50 20 48 8b 43 20 48 85 c0 0f 84 4d 02 00 00 48 8b 43 08 48 63 50 08 48 8b 44 d0 10 48 8d 15 99 fb ff ff <48> 8b a8 08 03 00 00 48 8b 05 9b fd 0e 00 48 8b 38 48 8b 07 48 8b
Oct 04 10:33:58 hostname kernel: kalendarac[1928]: segfault at 328 ip 00007fc3ec2bf957 sp 00007ffd310ea4d0 error 4 in libQt5XcbQpa.so.5.15.10[7fc3ec2b2000+9a000] likely on CPU 2 (core 2, socket 0)
Oct 04 10:33:58 hostname kernel: Code: ff 74 0a 48 8b 07 ff 50 20 48 8b 43 20 48 85 c0 0f 84 4d 02 00 00 48 8b 43 08 48 63 50 08 48 8b 44 d0 10 48 8d 15 99 fb ff ff <48> 8b a8 08 03 00 00 48 8b 05 9b fd 0e 00 48 8b 38 48 8b 07 48 8b
Oct 04 10:33:58 hostname systemd[1]: Started Process Core Dump (PID 1963/UID 0).
...
Oct 04 10:33:58 hostname systemd-coredump[1967]: Process 1929 (xdg-desktop-por) of user 1000 dumped core.

Stack trace of thread 1929:
#0 0x00007f38bd313957 _ZN15QXcbIntegration10initializeEv (libQt5XcbQpa.so.5 + 0x42957)
#1 0x00007f38c273fac2 _ZN22QGuiApplicationPrivate20eventDispatcherReadyEv (libQt5Gui.so.5 + 0x13fac2)
#2 0x00007f38c229b5d7 _ZN23QCoreApplicationPrivate4initEv (libQt5Core.so.5 + 0x29b5d7)
#3 0x00007f38c273fb16 _ZN22QGuiApplicationPrivate4initEv (libQt5Gui.so.5 + 0x13fb16)
#4 0x00007f38c3b75b9e _ZN19QApplicationPrivate4initEv (libQt5Widgets.so.5 + 0x175b9e)
#5 0x0000563332b460f4 n/a (xdg-desktop-portal-kde + 0x250f4)
#6 0x00007f38c1a45cd0 n/a (libc.so.6 + 0x27cd0)
#7 0x00007f38c1a45d8a __libc_start_main (libc.so.6 + 0x27d8a)
#8 0x0000563332b47645 n/a (xdg-desktop-portal-kde + 0x26645)

Stack trace of thread 1962:
#0 0x00007f38c1b20f6f __poll (libc.so.6 + 0x102f6f)
#1 0x00007f38c056c206 n/a (libglib-2.0.so.0 + 0xb8206)
#2 0x00007f38c050c112 g_main_context_iteration (libglib-2.0.so.0 + 0x58112)
#3 0x00007f38c22eaa1c _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2eaa1c)
#4 0x00007f38c229a904 _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x29a904)
#5 0x00007f38c20f73b6 _ZN7QThread4execEv (libQt5Core.so.5 + 0xf73b6)
#6 0x00007f38c3231a9a n/a (libQt5DBus.so.5 + 0x18a9a)
#7 0x00007f38c20f35da n/a (libQt5Core.so.5 + 0xf35da)
#8 0x00007f38c1aaa9eb n/a (libc.so.6 + 0x8c9eb)
#9 0x00007f38c1b2e7cc n/a (libc.so.6 + 0x1107cc)
ELF object binary architecture: AMD x86-64
-- Subject: Process 1929 (xdg-desktop-por) dumped core
-- The job identifier is 579 and the job result is failed.
Oct 04 10:33:58 hostname systemd-coredump[1964]: Process 1957 (kglobalaccel5) of user 1000 dumped core.

Stack trace of thread 1957:
#0 0x00007f68db10d957 _ZN15QXcbIntegration10initializeEv (libQt5XcbQpa.so.5 + 0x42957)
#1 0x00007f68df93fac2 _ZN22QGuiApplicationPrivate20eventDispatcherReadyEv (libQt5Gui.so.5 + 0x13fac2)
#2 0x00007f68df49b5d7 _ZN23QCoreApplicationPrivate4initEv (libQt5Core.so.5 + 0x29b5d7)
#3 0x00007f68df93fb16 _ZN22QGuiApplicationPrivate4initEv (libQt5Gui.so.5 + 0x13fb16)
#4 0x00007f68df94084c _ZN15QGuiApplicationC1ERiPPci (libQt5Gui.so.5 + 0x14084c)
#5 0x0000557386d3b0a2 n/a (kglobalaccel5 + 0x20a2)
#6 0x00007f68dec45cd0 n/a (libc.so.6 + 0x27cd0)
#7 0x00007f68dec45d8a __libc_start_main (libc.so.6 + 0x27d8a)
#8 0x0000557386d3b4a5 n/a (kglobalaccel5 + 0x24a5)

Stack trace of thread 1960:
#0 0x00007f68ded20f6f __poll (libc.so.6 + 0x102f6f)
#1 0x00007f68ddf6c206 n/a (libglib-2.0.so.0 + 0xb8206)
#2 0x00007f68ddf0c112 g_main_context_iteration (libglib-2.0.so.0 + 0x58112)
#3 0x00007f68df4eaa1c _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2eaa1c)
#4 0x00007f68df49a904 _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x29a904)
#5 0x00007f68df2f73b6 _ZN7QThread4execEv (libQt5Core.so.5 + 0xf73b6)
#6 0x00007f68df797a9a n/a (libQt5DBus.so.5 + 0x18a9a)
#7 0x00007f68df2f35da n/a (libQt5Core.so.5 + 0xf35da)
#8 0x00007f68decaa9eb n/a (libc.so.6 + 0x8c9eb)
#9 0x00007f68ded2e7cc n/a (libc.so.6 + 0x1107cc)
ELF object binary architecture: AMD x86-64
-- Subject: Process 1957 (kglobalaccel5) dumped core


-- The job identifier is 648.
Oct 04 10:33:59 hostname sddm[1113]: Setting default cursor
Oct 04 10:33:59 hostname kglobalaccel5[1995]: Authorization required, but no authorization protocol specified
Oct 04 10:33:59 hostname kglobalaccel5[1995]: Authorization required, but no authorization protocol specified
Oct 04 10:33:59 hostname kglobalaccel5[1995]: qt.qpa.xcb: could not connect to display :0
Oct 04 10:33:59 hostname sddm[1113]: Running display setup script "/usr/share/sddm/scripts/Xsetup"
Oct 04 10:33:59 hostname kernel: kglobalaccel5[1995]: segfault at 299fe6a7839d ip 00007fe5a990d957 sp 00007ffd8879bfe0 error 4 in libQt5XcbQpa.so.5.15.10[7fe5a9900000+9a000] likely on CPU 2 (core 2, socket 0)
Oct 04 10:33:59 hostname kernel: Code: ff 74 0a 48 8b 07 ff 50 20 48 8b 43 20 48 85 c0 0f 84 4d 02 00 00 48 8b 43 08 48 63 50 08 48 8b 44 d0 10 48 8d 15 99 fb ff ff <48> 8b a8 08 03 00 00 48 8b 05 9b fd 0e 00 48 8b 38 48 8b 07 48 8b
Oct 04 10:33:59 hostname sddm[1113]: Display server started.
Oct 04 10:33:59 hostname sddm[1113]: Socket server starting...
Oct 04 10:33:59 hostname sddm[1113]: Socket server started.
Oct 04 10:33:59 hostname sddm[1113]: Loaded empty theme configuration
Oct 04 10:33:59 hostname sddm[1113]: Greeter starting...
Oct 04 10:33:59 hostname sddm-helper[2001]: [PAM] Starting...
Oct 04 10:33:59 hostname sddm-helper[2001]: [PAM] Authenticating...
Oct 04 10:33:59 hostname sddm-helper[2001]: pam_unix(sddm-greeter:session): session opened for user sddm(uid=996) by (uid=0)
Oct 04 10:33:59 hostname sddm-helper[2001]: [PAM] returning.
Oct 04 10:33:59 hostname systemd[1]: Started Process Core Dump (PID 1999/UID 0).

Oct 04 10:33:59 hostname systemd-coredump[1968]: Process 1928 (kalendarac) of user 1000 dumped core.

Stack trace of thread 1928:
#0 0x00007fc3ec2bf957 _ZN15QXcbIntegration10initializeEv (libQt5XcbQpa.so.5 + 0x42957)
#1 0x00007fc40b13fac2 _ZN22QGuiApplicationPrivate20eventDispatcherReadyEv (libQt5Gui.so.5 + 0x13fac2)
#2 0x00007fc40ac9b5d7 _ZN23QCoreApplicationPrivate4initEv (libQt5Core.so.5 + 0x29b5d7)
#3 0x00007fc40b13fb16 _ZN22QGuiApplicationPrivate4initEv (libQt5Gui.so.5 + 0x13fb16)
#4 0x00007fc40b14084c _ZN15QGuiApplicationC1ERiPPci (libQt5Gui.so.5 + 0x14084c)
#5 0x000055b3a9f3d4d6 n/a (kalendarac + 0x84d6)
#6 0x00007fc40a445cd0 n/a (libc.so.6 + 0x27cd0)
#7 0x00007fc40a445d8a __libc_start_main (libc.so.6 + 0x27d8a)
#8 0x000055b3a9f3e655 n/a (kalendarac + 0x9655)

Stack trace of thread 1961:
#0 0x00007fc40a520f6f __poll (libc.so.6 + 0x102f6f)
#1 0x00007fc40856c206 n/a (libglib-2.0.so.0 + 0xb8206)
#2 0x00007fc40850c112 g_main_context_iteration (libglib-2.0.so.0 + 0x58112)
#3 0x00007fc40aceaa1c _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2eaa1c)
#4 0x00007fc40ac9a904 _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x29a904)
#5 0x00007fc40aaf73b6 _ZN7QThread4execEv (libQt5Core.so.5 + 0xf73b6)
#6 0x00007fc40b7baa9a n/a (libQt5DBus.so.5 + 0x18a9a)
#7 0x00007fc40aaf35da n/a (libQt5Core.so.5 + 0xf35da)
#8 0x00007fc40a4aa9eb n/a (libc.so.6 + 0x8c9eb)
#9 0x00007fc40a52e7cc n/a (libc.so.6 + 0x1107cc)
ELF object binary architecture: AMD x86-64


Oct 04 10:33:59 hostname sddm-greeter[2010]: Connected to the daemon.
Oct 04 10:33:59 hostname sddm[1113]: Message received from greeter: Connect
Oct 04 10:33:59 hostname systemd-coredump[2002]: Process 1995 (kglobalaccel5) of user 1000 dumped core.

Stack trace of thread 1995:
#0 0x00007fe5a990d957 _ZN15QXcbIntegration10initializeEv (libQt5XcbQpa.so.5 + 0x42957)
#1 0x00007fe5ae13fac2 _ZN22QGuiApplicationPrivate20eventDispatcherReadyEv (libQt5Gui.so.5 + 0x13fac2)
#2 0x00007fe5adc9b5d7 _ZN23QCoreApplicationPrivate4initEv (libQt5Core.so.5 + 0x29b5d7)
#3 0x00007fe5ae13fb16 _ZN22QGuiApplicationPrivate4initEv (libQt5Gui.so.5 + 0x13fb16)
#4 0x00007fe5ae14084c _ZN15QGuiApplicationC1ERiPPci (libQt5Gui.so.5 + 0x14084c)
#5 0x00005645c5f0b0a2 n/a (kglobalaccel5 + 0x20a2)
#6 0x00007fe5ad445cd0 n/a (libc.so.6 + 0x27cd0)
#7 0x00007fe5ad445d8a __libc_start_main (libc.so.6 + 0x27d8a)
#8 0x00005645c5f0b4a5 n/a (kglobalaccel5 + 0x24a5)

Stack trace of thread 1998:
#0 0x00007fe5ad520f6f __poll (libc.so.6 + 0x102f6f)
#1 0x00007fe5acb6c206 n/a (libglib-2.0.so.0 + 0xb8206)
#2 0x00007fe5acb0c112 g_main_context_iteration (libglib-2.0.so.0 + 0x58112)
#3 0x00007fe5adceaa1c _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2eaa1c)
#4 0x00007fe5adc9a904 _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x29a904)
#5 0x00007fe5adaf73b6 _ZN7QThread4execEv (libQt5Core.so.5 + 0xf73b6)
#6 0x00007fe5ae70fa9a n/a (libQt5DBus.so.5 + 0x18a9a)
#7 0x00007fe5adaf35da n/a (libQt5Core.so.5 + 0xf35da)
#8 0x00007fe5ad4aa9eb n/a (libc.so.6 + 0x8c9eb)
#9 0x00007fe5ad52e7cc n/a (libc.so.6 + 0x1107cc)
ELF object binary architecture: AMD x86-64


Oct 04 10:33:59 hostname kglobalaccel5[2045]: Authorization required, but no authorization protocol specified
Oct 04 10:33:59 hostname kglobalaccel5[2045]: Authorization required, but no authorization protocol specified
Oct 04 10:33:59 hostname kglobalaccel5[2045]: qt.qpa.xcb: could not connect to display :0
Oct 04 10:33:59 hostname kernel: kglobalaccel5[2045]: segfault at 293a2f58639d ip 00007f55be90d957 sp 00007ffd92dee3e0 error 4 in libQt5XcbQpa.so.5.15.10[7f55be900000+9a000] likely on CPU 3 (core 3, socket 0)
Oct 04 10:33:59 hostname kernel: Code: ff 74 0a 48 8b 07 ff 50 20 48 8b 43 20 48 85 c0 0f 84 4d 02 00 00 48 8b 43 08 48 63 50 08 48 8b 44 d0 10 48 8d 15 99 fb ff ff <48> 8b a8 08 03 00 00 48 8b 05 9b fd 0e 00 48 8b 38 48 8b 07 48 8b
Oct 04 10:33:59 hostname systemd[1]: Started Process Core Dump (PID 2047/UID 0).
-- Subject: A start job for unit systemd-coredump@4-2047-0.service has finished successfully
-- Defined-By: systemd
-- Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- A start job for unit systemd-coredump@4-2047-0.service has finished successfully.
--
-- The job identifier is 1959.
Oct 04 10:33:59 hostname systemd-coredump[2048]: Process 2045 (kglobalaccel5) of user 1000 dumped core.

Stack trace of thread 2045:
#0 0x00007f55be90d957 _ZN15QXcbIntegration10initializeEv (libQt5XcbQpa.so.5 + 0x42957)
#1 0x00007f55c313fac2 _ZN22QGuiApplicationPrivate20eventDispatcherReadyEv (libQt5Gui.so.5 + 0x13fac2)
#2 0x00007f55c2c9b5d7 _ZN23QCoreApplicationPrivate4initEv (libQt5Core.so.5 + 0x29b5d7)
#3 0x00007f55c313fb16 _ZN22QGuiApplicationPrivate4initEv (libQt5Gui.so.5 + 0x13fb16)
#4 0x00007f55c314084c _ZN15QGuiApplicationC1ERiPPci (libQt5Gui.so.5 + 0x14084c)
#5 0x0000561b93d170a2 n/a (kglobalaccel5 + 0x20a2)
#6 0x00007f55c2445cd0 n/a (libc.so.6 + 0x27cd0)
#7 0x00007f55c2445d8a __libc_start_main (libc.so.6 + 0x27d8a)
#8 0x0000561b93d174a5 n/a (kglobalaccel5 + 0x24a5)

Stack trace of thread 2046:
#0 0x00007f55c2520f6f __poll (libc.so.6 + 0x102f6f)
#1 0x00007f55c1b6c206 n/a (libglib-2.0.so.0 + 0xb8206)
#2 0x00007f55c1b0c112 g_main_context_iteration (libglib-2.0.so.0 + 0x58112)
#3 0x00007f55c2ceaa1c _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2eaa1c)
#4 0x00007f55c2c9a904 _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x29a904)
#5 0x00007f55c2af73b6 _ZN7QThread4execEv (libQt5Core.so.5 + 0xf73b6)
#6 0x00007f55c36a6a9a n/a (libQt5DBus.so.5 + 0x18a9a)
#7 0x00007f55c2af35da n/a (libQt5Core.so.5 + 0xf35da)
#8 0x00007f55c24aa9eb n/a (libc.so.6 + 0x8c9eb)
#9 0x00007f55c252e7cc n/a (libc.so.6 + 0x1107cc)
ELF object binary architecture: AMD x86-64






Oct 04 10:36:00 hostname kmix[2663]: The X11 connection broke: I/O error (code 1)
Oct 04 10:36:00 hostname ksmserver[2663]: XIO: fatal IO error 25 (Inappropriate ioctl for device) on X server ":0"
Oct 04 10:36:00 hostname ksmserver[2663]: after 321 requests (321 known processed) with 0 events remaining.
Oct 04 10:36:00 hostname dde-widgets[2679]: QXcbIntegration: Cannot create platform OpenGL context, neither GLX nor EGL are enabled
Oct 04 10:36:00 hostname dde-widgets[2679]: Warning: fallback to QtQuick software backend.
Oct 04 10:36:00 hostname xdg-desktop-portal-kde[2746]: qt.qpa.xcb: could not connect to display :0
Oct 04 10:36:00 hostname kernel: xdg-desktop-por[2746]: segfault at 298c2d27e23d ip 00007f48b230d957 sp 00007ffe7d8dc200 error 4 in libQt5XcbQpa.so.5.15.10[7f48b2300000+9a000] likely on CPU 1 (core 1, socket 0)
Oct 04 10:36:00 hostname kernel: Code: ff 74 0a 48 8b 07 ff 50 20 48 8b 43 20 48 85 c0 0f 84 4d 02 00 00 48 8b 43 08 48 63 50 08 48 8b 44 d0 10 48 8d 15 99 fb ff ff <48> 8b a8 08 03 00 00 48 8b 05 9b fd 0e 00 48 8b 38 48 8b 07 48 8b
Oct 04 10:36:00 hostname systemd[1]: Started Process Core Dump (PID 2758/UID 0).
-- Subject: A start job for unit systemd-coredump@5-2758-0.service has finished successfully
-- Defined-By: systemd
-- Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- A start job for unit systemd-coredump@5-2758-0.service has finished successfully.
--
-- The job identifier is 2157.
Oct 04 10:36:00 hostname acpid[589]: client 1971[0:0] has disconnected
Oct 04 10:36:00 hostname sddm[1113]: Display server stopped.
Oct 04 10:36:00 hostname sddm[1113]: Running display stop script ("/usr/share/sddm/scripts/Xstop")
Oct 04 10:36:00 hostname sddm[1113]: Removing display SDDM::Display(0x562259cda490) ...
Oct 04 10:36:00 hostname sddm[1113]: Adding new display...
Oct 04 10:36:00 hostname sddm[1113]: Loaded empty theme configuration
Oct 04 10:36:00 hostname sddm[1113]: Xauthority path: "/run/sddm/xauth_iQyhFP"
Oct 04 10:36:00 hostname sddm[1113]: Using VT 2
Oct 04 10:36:00 hostname sddm[1113]: Display server starting...
Oct 04 10:36:00 hostname sddm[1113]: Writing cookie to "/run/sddm/xauth_iQyhFP"
Oct 04 10:36:00 hostname sddm[1113]: Running: /usr/bin/X -nolisten tcp -background none -seat seat0 vt2 -auth /run/sddm/xauth_iQyhFP -noreset -displayfd 18
Oct 04 10:36:00 hostname systemd-coredump[2759]: Process 2746 (xdg-desktop-por) of user 1000 dumped core.

Stack trace of thread 2746:
#0 0x00007f48b230d957 _ZN15QXcbIntegration10initializeEv (libQt5XcbQpa.so.5 + 0x42957)
#1 0x00007f48b7b3fac2 _ZN22QGuiApplicationPrivate20eventDispatcherReadyEv (libQt5Gui.so.5 + 0x13fac2)
#2 0x00007f48b769b5d7 _ZN23QCoreApplicationPrivate4initEv (libQt5Core.so.5 + 0x29b5d7)
#3 0x00007f48b7b3fb16 _ZN22QGuiApplicationPrivate4initEv (libQt5Gui.so.5 + 0x13fb16)
#4 0x00007f48b8f75b9e _ZN19QApplicationPrivate4initEv (libQt5Widgets.so.5 + 0x175b9e)
#5 0x000055bc8a44f0f4 n/a (xdg-desktop-portal-kde + 0x250f4)
#6 0x00007f48b6e45cd0 n/a (libc.so.6 + 0x27cd0)
#7 0x00007f48b6e45d8a __libc_start_main (libc.so.6 + 0x27d8a)
#8 0x000055bc8a450645 n/a (xdg-desktop-portal-kde + 0x26645)

Stack trace of thread 2757:
#0 0x00007f48b6f20f6f __poll (libc.so.6 + 0x102f6f)
#1 0x00007f48b596c206 n/a (libglib-2.0.so.0 + 0xb8206)
#2 0x00007f48b590c112 g_main_context_iteration (libglib-2.0.so.0 + 0x58112)
#3 0x00007f48b76eaa1c _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2eaa1c)
#4 0x00007f48b769a904 _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x29a904)
#5 0x00007f48b74f73b6 _ZN7QThread4execEv (libQt5Core.so.5 + 0xf73b6)
#6 0x00007f48b8631a9a n/a (libQt5DBus.so.5 + 0x18a9a)
#7 0x00007f48b74f35da n/a (libQt5Core.so.5 + 0xf35da)
#8 0x00007f48b6eaa9eb n/a (libc.so.6 + 0x8c9eb)
#9 0x00007f48b6f2e7cc n/a (libc.so.6 + 0x1107cc)
ELF object binary architecture: AMD x86-64

Oct 04 10:36:01 hostname dde-widgets[2679]: Qt: Session management error: Could not open network socket
Oct 04 10:36:01 hostname kernel: dde-widgets[2679]: segfault at 8 ip 00007f3679b66ae4 sp 00007ffcf874a5e0 error 4 in libstartup-notification-1.so.0.0.0[7f3679b66000+4000] likely on CPU 5 (core 1, socket 0)
Oct 04 10:36:01 hostname kernel: Code: e6 48 89 ef 49 83 c4 01 ff 15 68 63 00 00 49 89 45 00 44 39 63 50 7f de 44 89 fe 48 8b 7b 10 31 d2 ff 15 17 64 00 00 48 89 c7 <8b> 40 08 89 43 20 ff 15 68 62 00 00 44 89 f6 48 8b 7b 10 31 d2 ff
Oct 04 10:36:01 hostname systemd[2787]: Starting D-Bus User Message Bus...
-- Subject: A start job for unit UNIT has begun execution
-- Defined-By: systemd
-- Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- A start job for unit UNIT has begun execution.
--
-- The job identifier is 27.
Oct 04 10:36:01 hostname systemd[1]: Started Process Core Dump (PID 2805/UID 0).
-- Subject: A start job for unit systemd-coredump@6-2805-0.service has finished successfully
-- Defined-By: systemd
-- Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- A start job for unit systemd-coredump@6-2805-0.service has finished successfully.
--
-- The job identifier is 2349.
Oct 04 10:36:01 hostname systemd[2787]: Started D-Bus User Message Bus.
-- Subject: A start job for unit UNIT has finished successfully
-- Defined-By: systemd
-- Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- A start job for unit UNIT has finished successfully.
--
-- The job identifier is 27.
Oct 04 10:36:01 hostname sddm-greeter[2801]: Connected to the daemon.
Oct 04 10:36:01 hostname sddm[1113]: Message received from greeter: Connect
Oct 04 10:36:01 hostname sddm-greeter[2801]: Loading qrc:/theme/Main.qml...
Oct 04 10:36:01 hostname sddm-greeter[2801]: file:///usr/lib/qt/qml/SddmComponents/LayoutBox.qml:35:5: QML Connections: Implicitly defined onFoo properties in Connections are deprecated. Use this syntax instead: function onFoo(<arguments>) { ... }
Oct 04 10:36:01 hostname systemd-coredump[2806]: Process 2679 (dde-widgets) of user 1000 dumped core.

Stack trace of thread 2679:
#0 0x00007f3679b66ae4 sn_xcb_display_new (libstartup-notification-1.so.0 + 0x3ae4)
#1 0x00007f3679a5904b _ZN26StartupNotificationMonitorC1Ev (libdtkwidget.so.5 + 0x25904b)
#2 0x00007f3679a5910c _ZN26StartupNotificationMonitor8instanceEv (libdtkwidget.so.5 + 0x25910c)
#3 0x00007f367995d824 _ZN3Dtk6Widget19DApplicationPrivateC1EPNS0_12DApplicationE (libdtkwidget.so.5 + 0x15d824)
#4 0x00007f367995da4a _ZN3Dtk6Widget12DApplicationC2ERiPPc (libdtkwidget.so.5 + 0x15da4a)
#5 0x000056507711fc52 n/a (dde-widgets + 0x28c52)
#6 0x00007f3677c45cd0 n/a (libc.so.6 + 0x27cd0)
#7 0x00007f3677c45d8a __libc_start_main (libc.so.6 + 0x27d8a)
#8 0x0000565077120e85 n/a (dde-widgets + 0x29e85)

Stack trace of thread 2708:
#0 0x00007f3677d20f6f __poll (libc.so.6 + 0x102f6f)
#1 0x00007f367795a206 n/a (libglib-2.0.so.0 + 0xb8206)
#2 0x00007f36778fa112 g_main_context_iteration (libglib-2.0.so.0 + 0x58112)
#3 0x00007f36784eaa1c _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2eaa1c)
#4 0x00007f367849a904 _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x29a904)
#5 0x00007f36782f73b6 _ZN7QThread4execEv (libQt5Core.so.5 + 0xf73b6)
#6 0x00007f3679797a9a n/a (libQt5DBus.so.5 + 0x18a9a)
#7 0x00007f36782f35da n/a (libQt5Core.so.5 + 0xf35da)
#8 0x00007f3677caa9eb n/a (libc.so.6 + 0x8c9eb)
#9 0x00007f3677d2e7cc n/a (libc.so.6 + 0x1107cc)
ELF object binary architecture: AMD x86-64




Oct 04 10:43:12 hostname xdg-desktop-portal-kde[2678]: qt.qpa.xcb: could not connect to display :0
Oct 04 10:43:12 hostname kernel: xdg-desktop-por[2678]: segfault at 29397227323d ip 00007f339010d957 sp 00007fffc0193590 error 4 in libQt5XcbQpa.so.5.15.10[7f3390100000+9a000] likely on CPU 7 (core 3, socket 0)
Oct 04 10:43:12 hostname kernel: Code: ff 74 0a 48 8b 07 ff 50 20 48 8b 43 20 48 85 c0 0f 84 4d 02 00 00 48 8b 43 08 48 63 50 08 48 8b 44 d0 10 48 8d 15 99 fb ff ff <48> 8b a8 08 03 00 00 48 8b 05 9b fd 0e 00 48 8b 38 48 8b 07 48 8b
Oct 04 10:43:12 hostname systemd[1]: Started Process Core Dump (PID 2686/UID 0).
-- Subject: A start job for unit systemd-coredump@6-2686-0.service has finished successfully
-- Defined-By: systemd
-- Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- A start job for unit systemd-coredump@6-2686-0.service has finished successfully.
--
-- The job identifier is 2063.
Oct 04 10:43:13 hostname sddm[1093]: Display server stopped.
Oct 04 10:43:13 hostname sddm[1093]: Running display stop script ("/usr/share/sddm/scripts/Xstop")
Oct 04 10:43:13 hostname sddm[1093]: Removing display SDDM::Display(0x55f73e66ece0) ...
Oct 04 10:43:13 hostname sddm[1093]: Adding new display...
Oct 04 10:43:13 hostname sddm[1093]: Loaded empty theme configuration
Oct 04 10:43:13 hostname sddm[1093]: Xauthority path: "/run/sddm/xauth_DiNqOZ"
Oct 04 10:43:13 hostname sddm[1093]: Using VT 2
Oct 04 10:43:13 hostname sddm[1093]: Display server starting...
Oct 04 10:43:13 hostname sddm[1093]: Writing cookie to "/run/sddm/xauth_DiNqOZ"
Oct 04 10:43:13 hostname sddm[1093]: Running: /usr/bin/X -nolisten tcp -background none -seat seat0 vt2 -auth /run/sddm/xauth_DiNqOZ -noreset -displayfd 18
Oct 04 10:43:13 hostname systemd-coredump[2687]: Process 2678 (xdg-desktop-por) of user 1000 dumped core.

Stack trace of thread 2678:
#0 0x00007f339010d957 _ZN15QXcbIntegration10initializeEv (libQt5XcbQpa.so.5 + 0x42957)
#1 0x00007f339593fac2 _ZN22QGuiApplicationPrivate20eventDispatcherReadyEv (libQt5Gui.so.5 + 0x13fac2)
#2 0x00007f339549b5d7 _ZN23QCoreApplicationPrivate4initEv (libQt5Core.so.5 + 0x29b5d7)
#3 0x00007f339593fb16 _ZN22QGuiApplicationPrivate4initEv (libQt5Gui.so.5 + 0x13fb16)
#4 0x00007f3396d75b9e _ZN19QApplicationPrivate4initEv (libQt5Widgets.so.5 + 0x175b9e)
#5 0x000055fa229850f4 n/a (xdg-desktop-portal-kde + 0x250f4)
#6 0x00007f3394c45cd0 n/a (libc.so.6 + 0x27cd0)
#7 0x00007f3394c45d8a __libc_start_main (libc.so.6 + 0x27d8a)
#8 0x000055fa22986645 n/a (xdg-desktop-portal-kde + 0x26645)

Stack trace of thread 2685:
#0 0x00007f3394d20f6f __poll (libc.so.6 + 0x102f6f)
#1 0x00007f339376c206 n/a (libglib-2.0.so.0 + 0xb8206)
#2 0x00007f339370c112 g_main_context_iteration (libglib-2.0.so.0 + 0x58112)
#3 0x00007f33954eaa1c _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2eaa1c)
#4 0x00007f339549a904 _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x29a904)
#5 0x00007f33952f73b6 _ZN7QThread4execEv (libQt5Core.so.5 + 0xf73b6)
#6 0x00007f3396431a9a n/a (libQt5DBus.so.5 + 0x18a9a)
#7 0x00007f33952f35da n/a (libQt5Core.so.5 + 0xf35da)
#8 0x00007f3394caa9eb n/a (libc.so.6 + 0x8c9eb)
#9 0x00007f3394d2e7cc n/a (libc.so.6 + 0x1107cc)
ELF object binary architecture: AMD x86-64




Oct 04 10:53:42 hostname kmix[4775]: The X11 connection broke: I/O error (code 1)
Oct 04 10:53:42 hostname ksmserver[4775]: XIO: fatal IO error 25 (Inappropriate ioctl for device) on X server ":0"
Oct 04 10:53:42 hostname ksmserver[4775]: after 321 requests (321 known processed) with 0 events remaining.
Oct 04 10:53:42 hostname xdg-desktop-portal-kde[4852]: qt.qpa.xcb: could not connect to display :0
Oct 04 10:53:42 hostname kernel: xdg-desktop-por[4852]: segfault at 29cae1ec212d ip 00007f8e66b27957 sp 00007ffe642da300 error 4 in libQt5XcbQpa.so.5.15.10[7f8e66b1a000+9a000] likely on CPU 4 (core 0, socket 0)
Oct 04 10:53:42 hostname kernel: Code: ff 74 0a 48 8b 07 ff 50 20 48 8b 43 20 48 85 c0 0f 84 4d 02 00 00 48 8b 43 08 48 63 50 08 48 8b 44 d0 10 48 8d 15 99 fb ff ff <48> 8b a8 08 03 00 00 48 8b 05 9b fd 0e 00 48 8b 38 48 8b 07 48 8b
Oct 04 10:53:42 hostname systemd[1]: Started Process Core Dump (PID 4869/UID 0).
-- Subject: A start job for unit systemd-coredump@7-4869-0.service has finished successfully
-- Defined-By: systemd
-- Support: https://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- A start job for unit systemd-coredump@7-4869-0.service has finished successfully.
--
-- The job identifier is 3093.
Oct 04 10:53:42 hostname sddm[1093]: Display server stopped.
Oct 04 10:53:42 hostname sddm[1093]: Running display stop script ("/usr/share/sddm/scripts/Xstop")
Oct 04 10:53:42 hostname sddm[1093]: Removing display SDDM::Display(0x55f73e6c33d0) ...
Oct 04 10:53:42 hostname sddm[1093]: Adding new display...
Oct 04 10:53:42 hostname sddm[1093]: Loaded empty theme configuration
Oct 04 10:53:42 hostname sddm[1093]: Xauthority path: "/run/sddm/xauth_XDHqWd"
Oct 04 10:53:42 hostname sddm[1093]: Using VT 1
Oct 04 10:53:42 hostname sddm[1093]: Display server starting...
Oct 04 10:53:42 hostname sddm[1093]: Writing cookie to "/run/sddm/xauth_XDHqWd"
Oct 04 10:53:42 hostname sddm[1093]: Running: /usr/bin/X -nolisten tcp -background none -seat seat0 vt1 -auth /run/sddm/xauth_XDHqWd -noreset -displayfd 18
Oct 04 10:53:42 hostname systemd-coredump[4870]: Process 4852 (xdg-desktop-por) of user 1000 dumped core.

Stack trace of thread 4852:
#0 0x00007f8e66b27957 _ZN15QXcbIntegration10initializeEv (libQt5XcbQpa.so.5 + 0x42957)
#1 0x00007f8e6bf3fac2 _ZN22QGuiApplicationPrivate20eventDispatcherReadyEv (libQt5Gui.so.5 + 0x13fac2)
#2 0x00007f8e6ba9b5d7 _ZN23QCoreApplicationPrivate4initEv (libQt5Core.so.5 + 0x29b5d7)
#3 0x00007f8e6bf3fb16 _ZN22QGuiApplicationPrivate4initEv (libQt5Gui.so.5 + 0x13fb16)
#4 0x00007f8e6d375b9e _ZN19QApplicationPrivate4initEv (libQt5Widgets.so.5 + 0x175b9e)
#5 0x000055c3899550f4 n/a (xdg-desktop-portal-kde + 0x250f4)
#6 0x00007f8e6b245cd0 n/a (libc.so.6 + 0x27cd0)
#7 0x00007f8e6b245d8a __libc_start_main (libc.so.6 + 0x27d8a)
#8 0x000055c389956645 n/a (xdg-desktop-portal-kde + 0x26645)

Stack trace of thread 4868:
#0 0x00007f8e6b320f6f __poll (libc.so.6 + 0x102f6f)
#1 0x00007f8e69d6c206 n/a (libglib-2.0.so.0 + 0xb8206)
#2 0x00007f8e69d0c112 g_main_context_iteration (libglib-2.0.so.0 + 0x58112)
#3 0x00007f8e6baeaa1c _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2eaa1c)
#4 0x00007f8e6ba9a904 _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x29a904)
#5 0x00007f8e6b8f73b6 _ZN7QThread4execEv (libQt5Core.so.5 + 0xf73b6)
#6 0x00007f8e6ca31a9a n/a (libQt5DBus.so.5 + 0x18a9a)
#7 0x00007f8e6b8f35da n/a (libQt5Core.so.5 + 0xf35da)
#8 0x00007f8e6b2aa9eb n/a (libc.so.6 + 0x8c9eb)
#9 0x00007f8e6b32e7cc n/a (libc.so.6 + 0x1107cc)
ELF object binary architecture: AMD x86-64

Looks like something is badly broken with your graphics setup. xdg-desktop-portal-kde-5.27.8-2 is a simple rebuild so it can't break anything and, in any case, an xdg-desktop-portal failure should not be able to kill your session. You need to look in the X server log to see why it's being killed.

Document what I did to fix the issue.

I spent 3 HOURS trying everything I could think of and tearing out anything that broke and FINALLY stumbled across the root cause.

dde-widgets[...]: QXcbIntegration: Cannot create platform OpenGL context, neither GLX nor EGL are enabled

I had geeqie installed to view images from YEARS ago, which seems to have somehow pulled in the Deepin Desktop Environment (dde) at some point, though now clutter and other packages which it depends on don't.

If anyone else has similar issues, pamcan -R $(pacman -Qs deepin*) and add in anything after it that depends on a deepin package until you're liberated from the bug.