@acul71: Thanks for the report.

Can you elaborate in what environment you are trying to run qjackctl? I can not reproduce this on wayland (sway).
Can you provide the output of "echo $QT_QPA_PLATFORM".

If you are on wayland: do you have xorg-xwayland installed?

echo $QT_QPA_PLATFORM

(IS EMPTY)
echo $WAYLAND_DISPLAY

(IS EMPTY)

---------------------------------------
journalctl -r

Apr 09 16:38:50 i5 audit[1]: SERVICE_STOP pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-coredump@22-130428-0 comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? t>
Apr 09 16:38:50 i5 kernel: audit: type=1131 audit(1617979130.954:788): pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-coredump@22-130428-0 comm="systemd" exe="/usr/lib/systemd>
Apr 09 16:38:50 i5 systemd[1]: systemd-coredump@22-130428-0.service: Deactivated successfully.
Apr 09 16:38:50 i5 systemd-coredump[130429]: Process 130422 (qjackctl) of user 1000 dumped core.

Stack trace of thread 130422:
#0 0x00007fd2459ff230 main_arena (libc.so.6 + 0x1c2230)
Apr 09 16:38:50 i5 systemd[1]: Started Process Core Dump (PID 130428/UID 0).
Apr 09 16:38:50 i5 audit[1]: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-coredump@22-130428-0 comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? >
Apr 09 16:38:50 i5 kernel: audit: type=1130 audit(1617979130.660:787): pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=systemd-coredump@22-130428-0 comm="systemd" exe="/usr/lib/systemd>
Apr 09 16:38:50 i5 kernel: audit: type=1334 audit(1617979130.657:786): prog-id=222 op=LOAD
Apr 09 16:38:50 i5 kernel: audit: type=1334 audit(1617979130.657:785): prog-id=221 op=LOAD
Apr 09 16:38:50 i5 kernel: audit: type=1334 audit(1617979130.657:784): prog-id=220 op=LOAD
Apr 09 16:38:50 i5 audit: BPF prog-id=222 op=LOAD
Apr 09 16:38:50 i5 audit: BPF prog-id=221 op=LOAD
Apr 09 16:38:50 i5 audit: BPF prog-id=220 op=LOAD
Apr 09 16:38:50 i5 kernel: audit: type=1701 audit(1617979130.640:783): auid=1000 uid=1000 gid=1001 ses=1 pid=130422 comm="qjackctl" exe="/usr/bin/qjackctl" sig=11 res=1
Apr 09 16:38:50 i5 kernel: Code: 00 00 f0 f1 9f 45 d2 7f 00 00 00 f2 9f 45 d2 7f 00 00 00 f2 9f 45 d2 7f 00 00 10 f2 9f 45 d2 7f 00 00 10 f2 9f 45 d2 7f 00 00 <20> f2 9f 45 d2 7f 00 00 20 f>
Apr 09 16:38:50 i5 kernel: qjackctl[130422]: segfault at 7fd2459ff230 ip 00007fd2459ff230 sp 00007ffcd629de78 error 15 in libc-2.33.so[7fd2459fe000+3000]
Apr 09 16:38:50 i5 audit[130422]: ANOM_ABEND auid=1000 uid=1000 gid=1001 ses=1 pid=130422 comm="qjackctl" exe="/usr/bin/qjackctl" sig=11 res=1


-------------------
inxi -v7
System: Host: i5 Kernel: 5.11.11-arch1-1 x86_64 bits: 64 compiler: gcc v: 10.2.0 Desktop: GNOME 3.38.4 tk: GTK 3.24.28
wm: gnome-shell dm: GDM 3.38.2.1, LightDM 1.30.0 Distro: Arch Linux
Machine: Type: Desktop Mobo: ASUSTeK model: P7P55D LE v: Rev 1.xx serial: <superuser required> BIOS: American Megatrends
v: 2101 date: 10/03/2012
Memory: RAM: total: 15.63 GiB used: 5.89 GiB (37.7%)
RAM Report: permissions: Unable to run dmidecode. Root privileges required.
CPU: Info: Quad Core model: Intel Xeon X3480 bits: 64 type: MT MCP arch: Nehalem rev: 5 cache: L2: 8 MiB bogomips: 49241
Speed: 1204 MHz min/max: 1200/3068 MHz boost: enabled Core speeds (MHz): 1: 1204 2: 1204 3: 1204 4: 1204 5: 1203
6: 1204 7: 1204 8: 1204
Flags: acpi aperfmperf apic arch_perfmon bts clflush cmov constant_tsc cpuid cx16 cx8 de ds_cpl dtes64 dtherm dts
ept est flexpriority fpu fxsr ht ida lahf_lm lm mca mce mmx monitor msr mtrr nonstop_tsc nopl nx pae pat pbe pdcm
pebs pge pni popcnt pse pse36 pti rdtscp rep_good sep smx sse sse2 sse4_1 sse4_2 ssse3 syscall tm tm2 tpr_shadow
tsc vme vmx vnmi vpid xtopology xtpr
Graphics: Device-1: NVIDIA GT218 [GeForce 210] vendor: CardExpert driver: nvidia v: 340.108 bus-ID: 01:00.0
chip-ID: 10de:0a65 class-ID: 0300
Display: x11 server: X.Org 1.20.10 compositor: gnome-shell driver: loaded: nvidia resolution: 1920x1080~60Hz
s-dpi: 96
OpenGL: renderer: GeForce 210/PCIe/SSE2 v: 3.3.0 NVIDIA 340.108 direct render: Yes
Audio: Device-1: Intel 5 Series/3400 Series High Definition Audio vendor: ASUSTeK driver: snd_hda_intel v: kernel
bus-ID: 00:1b.0 chip-ID: 8086:3b56 class-ID: 0403
Device-2: NVIDIA High Definition Audio vendor: CardExpert driver: snd_hda_intel v: kernel bus-ID: 01:00.1
chip-ID: 10de:0be3 class-ID: 0403
Sound Server-1: ALSA v: k5.11.11-arch1-1 running: yes
Sound Server-2: sndio v: N/A running: no
Sound Server-3: JACK v: 1.9.17 running: yes
Sound Server-4: PulseAudio v: 14.2 running: yes
Sound Server-5: PipeWire v: 0.3.24 running: yes
Network: Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet vendor: ASUSTeK M4A785/P7P55 driver: r8169
v: kernel port: d800 bus-ID: 02:00.0 chip-ID: 10ec:8168 class-ID: 0200
IF: enp2s0 state: up speed: 1000 Mbps duplex: full mac: e0:cb:4e:c3:9f:ef
IP v4: 192.168.1.103/24 type: dynamic noprefixroute scope: global broadcast: 192.168.1.255
IF-ID-1: wg-mullvad state: unknown speed: N/A duplex: N/A mac: N/A
IP v4: 10.70.113.198/32 scope: global
WAN IP: ;; Connection to 193.108.88.1#53(193.108.88.1) for whoami.akamai.net failed: connection refused.
Bluetooth: Message: No Bluetooth data was found.
Logical: Message: No LVM data was found.
RAID: Message: No RAID data was found.

pacman -Qs wayland
local/kodi-wayland 19.0-9
wayland kodi binary
local/kwayland 5.80.0-1 (kf5)
Qt-style Client and Server library wrapper for the Wayland libraries
local/lib32-wayland 1.19.0-1
A computer display server protocol
local/libva 2.11.0-1
Video Acceleration (VA) API for Linux
local/qt5-wayland 5.15.2-1 (qt qt5)
Provides APIs for Wayland
local/wayland 1.19.0-1
A computer display server protocol
local/wayland-protocols 1.20-1
Specifications of extended Wayland protocols
local/waylandpp 0.2.8-1
Wayland C++ bindings
local/xorg-xwayland 21.1.0-1 (xorg)
run X clients under wayland

-------------------------------------------

$ env
SHELL=/bin/bash
SESSION_MANAGER=local/i5:@/tmp/.ICE-unix/1020,unix/i5:/tmp/.ICE-unix/1020
COLORTERM=truecolor
XDG_MENU_PREFIX=gnome-
SSH_AUTH_SOCK=/run/user/1000/keyring/ssh
XDG_DATA_HOME=/home/luca/.local/share
XDG_CONFIG_HOME=/home/luca/.config
XMODIFIERS=@im=ibus
DESKTOP_SESSION=gnome
ANDROID_NDK=/opt/android-ndk
PWD=/home/luca/tmp/test
LOGNAME=luca
XDG_SESSION_DESKTOP=gnome
XDG_SESSION_TYPE=x11
DSSI_PATH=/home/luca/.dssi:/usr/lib/dssi:/usr/local/lib/dssi
SYSTEMD_EXEC_PID=1039
XAUTHORITY=/run/user/1000/gdm/Xauthority
AIR_HOME=/opt/adobe-air-sdk
WINDOWPATH=2
MOTD_SHOWN=pam
GDM_LANG=en_US.UTF-8
HOME=/home/luca
USERNAME=luca
LANG=en_US.UTF-8
VST_PATH=/home/luca/.vst:/usr/lib/vst:/usr/local/lib/vst
LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.wim=01;31:*.swm=01;31:*.dwm=01;31:*.esd=01;31:*.jpg=01;35:*.jpeg=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.webp=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:
XDG_CURRENT_DESKTOP=GNOME
VTE_VERSION=6400
GNOME_TERMINAL_SCREEN=/org/gnome/Terminal/screen/85659d3c_92ab_47f0_868a_f79dbcf83683
ANDROID_NDK_HOME=/opt/android-ndk
XDG_CACHE_HOME=/home/luca/.cache
XDG_SESSION_CLASS=user
ANDROID_HOME=/opt/android-sdk
TERM=xterm-256color
LESSOPEN=|/usr/bin/lesspipe.sh %s
USER=luca
GNOME_TERMINAL_SERVICE=:1.259
VISUAL=vim
DISPLAY=:1
SHLVL=1
QT_IM_MODULE=ibus
MOZ_PLUGIN_PATH=/usr/lib/mozilla/plugins
XDG_RUNTIME_DIR=/run/user/1000
HAXE_STD_PATH=/usr/share/haxe/std
XDG_DATA_DIRS=/home/luca/.local/share/flatpak/exports/share:/var/lib/flatpak/exports/share:/usr/local/share/:/usr/share/
PATH=/usr/local/bin:/usr/local/sbin:/usr/bin:/opt/adobe-air-sdk/bin:/opt/android-ndk:/opt/android-sdk/platform-tools:/opt/android-sdk/tools:/opt/android-sdk/tools/bin:/home/luca/.local/share/flatpak/exports/bin:/usr/lib/jvm/default/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/opt/adobe-air-sdk/bin:/opt/android-ndk:/opt/android-sdk/platform-tools:/opt/android-sdk/tools:/opt/android-sdk/tools/bin:/home/luca/.local/share/flatpak/exports/bin:/usr/lib/jvm/default/bin
GDMSESSION=gnome
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
LV2_PATH=/home/luca/.lv2:/usr/lib/lv2:/usr/local/lib/lv2
MAIL=/var/spool/mail/luca
LADSPA_PATH=/home/luca/.ladspa:/usr/lib/ladspa:/usr/local/lib/ladspa
CADENCE_AUTO_STARTED=true
OLDPWD=/home/luca/tmp
_=/usr/bin/env

---------------------------------------------------


[ 31.751] (--) Log file renamed from "/var/log/Xorg.pid-726.log" to "/var/log/Xorg.0.log"
[ 31.754] (WW) Failed to open protocol names file lib/xorg/protocol.txt
[ 31.754]
X.Org X Server 1.20.10
X Protocol Version 11, Revision 0
[ 31.754] Build Operating System: Linux Arch Linux
[ 31.754] Current Operating System: Linux i5 5.11.11-arch1-1 #1 SMP PREEMPT Tue, 30 Mar 2021 14:10:17 +0000 x86_64
[ 31.754] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-linux root=UUID=3f0c63cf-c7cc-46a2-8cba-fb4d51b76a89 rw quiet
[ 31.754] Build Date: 14 December 2020 12:10:29PM
[ 31.754]
[ 31.754] Current version of pixman: 0.40.0
[ 31.754] Before reporting problems, check http://wiki.x.org
to make sure that you have the latest version.
[ 31.754] Markers: (--) probed, (**) from config file, (==) default setting,
(++) from command line, (!!) notice, (II) informational,
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
[ 31.755] (==) Log file: "/var/log/Xorg.0.log", Time: Mon Apr 5 18:35:38 2021
[ 31.763] (==) Using config directory: "/etc/X11/xorg.conf.d"
[ 31.764] (==) Using system config directory "/usr/share/X11/xorg.conf.d"
[ 31.766] (==) No Layout section. Using the first Screen section.
[ 31.766] (==) No screen section available. Using defaults.
[ 31.766] (**) |-->Screen "Default Screen Section" (0)
[ 31.766] (**) | |-->Monitor "<default monitor>"
[ 31.767] (==) No device specified for screen "Default Screen Section".
Using the first device section listed.
[ 31.767] (**) | |-->Device "Nvidia card"
[ 31.767] (==) No monitor specified for screen "Default Screen Section".
Using a default monitor configuration.
[ 31.767] (==) Automatically adding devices
[ 31.767] (==) Automatically enabling devices
[ 31.767] (==) Automatically adding GPU devices
[ 31.767] (==) Automatically binding GPU devices
[ 31.767] (==) Max clients allowed: 256, resource mask: 0x1fffff
[ 31.774] (==) FontPath set to:
/usr/share/fonts/misc,
/usr/share/fonts/TTF,
/usr/share/fonts/OTF,
/usr/share/fonts/Type1,
/usr/share/fonts/100dpi,
/usr/share/fonts/75dpi
[ 31.774] (**) ModulePath set to "/usr/lib64/nvidia/xorg,/usr/lib64//xorg/modules"
[ 31.774] (II) The server relies on udev to provide the list of input devices.
If no devices become available, reconfigure udev or disable AutoAddDevices.
[ 31.774] (II) Module ABI versions:
[ 31.774] X.Org ANSI C Emulation: 0.4
[ 31.774] X.Org Video Driver: 24.1
[ 31.774] X.Org XInput driver : 24.1
[ 31.774] X.Org Server Extension : 10.0
[ 31.775] (++) using VT number 1

[ 31.779] (II) systemd-logind: took control of session /org/freedesktop/login1/session/_34
[ 31.783] (--) PCI:*(1@0:0:0) 10de:0a65:10b0:1401 rev 162, Mem @ 0xf6000000/16777216, 0xe0000000/268435456, 0xf2000000/33554432, I/O @ 0x0000cc00/128, BIOS @ 0x????????/131072
[ 31.783] (WW) Open ACPI failed (/var/run/acpid.socket) (No such file or directory)
[ 31.783] (II) LoadModule: "glx"
[ 31.784] (II) Loading /usr/lib64/nvidia/xorg/libglx.so
[ 31.987] (II) Module glx: vendor="NVIDIA Corporation"
[ 31.988] compiled for 4.0.2, module version = 1.0.0
[ 31.988] Module class: X.Org Server Extension
[ 31.988] (II) NVIDIA GLX Module 340.108 Wed Dec 11 14:26:50 PST 2019
[ 31.990] (II) LoadModule: "nvidia"
[ 31.993] (II) Loading /usr/lib64//xorg/modules/drivers/nvidia_drv.so
[ 32.006] (II) Module nvidia: vendor="NVIDIA Corporation"
[ 32.006] compiled for 4.0.2, module version = 1.0.0
[ 32.006] Module class: X.Org Video Driver
[ 32.007] (II) NVIDIA dlloader X Driver 340.108 Wed Dec 11 14:06:00 PST 2019
[ 32.007] (II) NVIDIA Unified Driver for all Supported NVIDIA GPUs
[ 32.010] (II) Loading sub module "fb"
[ 32.010] (II) LoadModule: "fb"
[ 32.010] (II) Loading /usr/lib64//xorg/modules/libfb.so
[ 32.011] (II) Module fb: vendor="X.Org Foundation"
[ 32.012] compiled for 1.20.10, module version = 1.0.0
[ 32.012] ABI class: X.Org ANSI C Emulation, version 0.4
[ 32.012] (WW) Unresolved symbol: fbGetGCPrivateKey
[ 32.012] (II) Loading sub module "wfb"
[ 32.012] (II) LoadModule: "wfb"
[ 32.012] (II) Loading /usr/lib64//xorg/modules/libwfb.so
[ 32.013] (II) Module wfb: vendor="X.Org Foundation"
[ 32.013] compiled for 1.20.10, module version = 1.0.0
[ 32.013] ABI class: X.Org ANSI C Emulation, version 0.4
[ 32.013] (II) Loading sub module "ramdac"
[ 32.013] (II) LoadModule: "ramdac"
[ 32.013] (II) Module "ramdac" already built-in
[ 32.016] (II) NVIDIA(0): Creating default Display subsection in Screen section
"Default Screen Section" for depth/fbbpp 24/32
[ 32.016] (==) NVIDIA(0): Depth 24, (==) framebuffer bpp 32
[ 32.016] (==) NVIDIA(0): RGB weight 888
[ 32.016] (==) NVIDIA(0): Default visual is TrueColor
[ 32.016] (==) NVIDIA(0): Using gamma correction (1.0, 1.0, 1.0)
[ 32.017] (**) NVIDIA(0): Enabling 2D acceleration
[ 32.661] (II) NVIDIA(0): Display (Samsung S23B550 (DFP-1)) does not support NVIDIA 3D
[ 32.661] (II) NVIDIA(0): Vision stereo.
[ 32.663] (II) NVIDIA(0): NVIDIA GPU GeForce 210 (GT218) at PCI:1:0:0 (GPU-0)
[ 32.663] (--) NVIDIA(0): Memory: 524288 kBytes
[ 32.663] (--) NVIDIA(0): VideoBIOS: 70.18.2d.00.00
[ 32.663] (II) NVIDIA(0): Detected PCI Express Link width: 16X
[ 32.667] (--) NVIDIA(0): Valid display device(s) on GeForce 210 at PCI:1:0:0
[ 32.667] (--) NVIDIA(0): CRT-0
[ 32.667] (--) NVIDIA(0): CRT-1
[ 32.667] (--) NVIDIA(0): DFP-0
[ 32.667] (--) NVIDIA(0): Samsung S23B550 (DFP-1) (boot, connected)
[ 32.667] (--) NVIDIA(GPU-0): CRT-0: 400.0 MHz maximum pixel clock
[ 32.667] (--) NVIDIA(GPU-0): CRT-1: 160.0 MHz maximum pixel clock
[ 32.667] (--) NVIDIA(0): DFP-0: Internal TMDS
[ 32.667] (--) NVIDIA(GPU-0): DFP-0: 330.0 MHz maximum pixel clock
[ 32.667] (--) NVIDIA(0): Samsung S23B550 (DFP-1): Internal TMDS
[ 32.667] (--) NVIDIA(GPU-0): Samsung S23B550 (DFP-1): 225.0 MHz maximum pixel clock
[ 32.667] (**) NVIDIA(0): Using HorizSync/VertRefresh ranges from the EDID for display
[ 32.668] (**) NVIDIA(0): device Samsung S23B550 (DFP-1) (Using EDID frequencies has
[ 32.668] (**) NVIDIA(0): been enabled on all display devices.)
[ 32.669] (WW) NVIDIA(GPU-0): The EDID for Samsung S23B550 (DFP-1) contradicts itself: mode
[ 32.669] (WW) NVIDIA(GPU-0): "1920x1080" is specified in the EDID; however, the EDID's
[ 32.669] (WW) NVIDIA(GPU-0): valid HorizSync range (30.000-81.000 kHz) would exclude
[ 32.669] (WW) NVIDIA(GPU-0): this mode's HorizSync (27.0 kHz); ignoring HorizSync check
[ 32.669] (WW) NVIDIA(GPU-0): for mode "1920x1080".
[ 32.671] (==) NVIDIA(0):
[ 32.671] (==) NVIDIA(0): No modes were requested; the default mode "nvidia-auto-select"
[ 32.671] (==) NVIDIA(0): will be used as the requested mode.
[ 32.671] (==) NVIDIA(0):
[ 32.671] (II) NVIDIA(0): Validated MetaModes:
[ 32.671] (II) NVIDIA(0): "DFP-1:nvidia-auto-select"
[ 32.671] (II) NVIDIA(0): Virtual screen size determined to be 1920 x 1080
[ 32.709] (--) NVIDIA(0): DPI set to (95, 94); computed from "UseEdidDpi" X config
[ 32.709] (--) NVIDIA(0): option
[ 32.710] (II) NVIDIA: Using 768.00 MB of virtual memory for indirect memory access.
[ 32.714] (II) NVIDIA(0): ACPI: failed to connect to the ACPI event daemon; the daemon
[ 32.714] (II) NVIDIA(0): may not be running or the "AcpidSocketPath" X
[ 32.714] (II) NVIDIA(0): configuration option may not be set correctly. When the
[ 32.714] (II) NVIDIA(0): ACPI event daemon is available, the NVIDIA X driver will
[ 32.714] (II) NVIDIA(0): try to use it to receive ACPI event notifications. For
[ 32.714] (II) NVIDIA(0): details, please see the "ConnectToAcpid" and
[ 32.714] (II) NVIDIA(0): "AcpidSocketPath" X configuration options in Appendix B: X
[ 32.714] (II) NVIDIA(0): Config Options in the README.
[ 32.718] (II) NVIDIA(0): Setting mode "DFP-1:nvidia-auto-select"
[ 32.829] (==) NVIDIA(0): Disabling shared memory pixmaps
[ 32.829] (==) NVIDIA(0): Backing store enabled
[ 32.829] (==) NVIDIA(0): Silken mouse disabled
[ 32.830] (==) NVIDIA(0): DPMS enabled
[ 32.830] (II) Loading sub module "dri2"
[ 32.830] (II) LoadModule: "dri2"
[ 32.830] (II) Module "dri2" already built-in
[ 32.830] (II) NVIDIA(0): [DRI2] Setup complete
[ 32.830] (II) NVIDIA(0): [DRI2] VDPAU driver: nvidia
[ 32.831] (II) Initializing extension Generic Event Extension
[ 32.831] (II) Initializing extension SHAPE
[ 32.831] (II) Initializing extension MIT-SHM
[ 32.831] (II) Initializing extension XInputExtension
[ 32.831] (II) Initializing extension XTEST
[ 32.831] (II) Initializing extension BIG-REQUESTS
[ 32.831] (II) Initializing extension SYNC
[ 32.831] (II) Initializing extension XKEYBOARD
[ 32.831] (II) Initializing extension XC-MISC
[ 32.831] (II) Initializing extension SECURITY
[ 32.831] (II) Initializing extension XFIXES
[ 32.831] (II) Initializing extension RENDER
[ 32.831] (II) Initializing extension RANDR
[ 32.831] (II) Initializing extension COMPOSITE
[ 32.831] (II) Initializing extension DAMAGE
[ 32.831] (II) Initializing extension MIT-SCREEN-SAVER
[ 32.831] (II) Initializing extension DOUBLE-BUFFER
[ 32.831] (II) Initializing extension RECORD
[ 32.831] (II) Initializing extension DPMS
[ 32.831] (II) Initializing extension Present
[ 32.831] (II) Initializing extension DRI3
[ 32.831] (II) Initializing extension X-Resource
[ 32.831] (II) Initializing extension XVideo
[ 32.831] (II) Initializing extension XVideo-MotionCompensation
[ 32.831] (II) Initializing extension XFree86-VidModeExtension
[ 32.831] (II) Initializing extension XFree86-DGA
[ 32.831] (II) Initializing extension XFree86-DRI
[ 32.831] (II) Initializing extension DRI2
[ 32.831] (II) Initializing extension GLX
[ 32.831] (II) Initializing extension GLX
[ 32.831] (II) Indirect GLX disabled.(II) Initializing extension NV-GLX
[ 32.831] (II) Initializing extension NV-CONTROL
[ 32.831] (II) Initializing extension XINERAMA
[ 32.959] (II) config/udev: Adding input device Power Button (/dev/input/event1)
[ 32.959] (**) Power Button: Applying InputClass "evdev keyboard catchall"
[ 32.959] (**) Power Button: Applying InputClass "libinput keyboard catchall"
[ 32.959] (II) LoadModule: "libinput"
[ 32.960] (II) Loading /usr/lib64//xorg/modules/input/libinput_drv.so
[ 32.966] (II) Module libinput: vendor="X.Org Foundation"
[ 32.966] compiled for 1.20.8, module version = 0.30.0
[ 32.966] Module class: X.Org XInput Driver
[ 32.966] ABI class: X.Org XInput driver, version 24.1
[ 32.966] (II) Using input driver 'libinput' for 'Power Button'
[ 32.967] (II) systemd-logind: got fd for /dev/input/event1 13:65 fd 29 paused 0
[ 32.968] (**) Power Button: always reports core events
[ 32.968] (**) Option "Device" "/dev/input/event1"
[ 32.968] (**) Option "_source" "server/udev"
[ 32.980] (II) event1 - Power Button: is tagged by udev as: Keyboard
[ 32.981] (II) event1 - Power Button: device is a keyboard
[ 32.981] (II) event1 - Power Button: device removed
[ 32.981] (**) Option "config_info" "udev:/sys/devices/LNXSYSTM:00/LNXPWRBN:00/input/input1/event1"
[ 32.981] (II) XINPUT: Adding extended input device "Power Button" (type: KEYBOARD, id 6)
[ 32.982] (II) event1 - Power Button: is tagged by udev as: Keyboard
[ 32.982] (II) event1 - Power Button: device is a keyboard
[ 32.983] (II) config/udev: Adding input device Power Button (/dev/input/event0)
[ 32.983] (**) Power Button: Applying InputClass "evdev keyboard catchall"
[ 32.983] (**) Power Button: Applying InputClass "libinput keyboard catchall"
[ 32.983] (II) Using input driver 'libinput' for 'Power Button'
[ 32.985] (II) systemd-logind: got fd for /dev/input/event0 13:64 fd 32 paused 0
[ 32.985] (**) Power Button: always reports core events
[ 32.985] (**) Option "Device" "/dev/input/event0"
[ 32.985] (**) Option "_source" "server/udev"
[ 32.986] (II) event0 - Power Button: is tagged by udev as: Keyboard
[ 32.987] (II) event0 - Power Button: device is a keyboard
[ 32.987] (II) event0 - Power Button: device removed
[ 32.987] (**) Option "config_info" "udev:/sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0C:00/input/input0/event0"
[ 32.987] (II) XINPUT: Adding extended input device "Power Button" (type: KEYBOARD, id 7)
[ 32.988] (II) event0 - Power Button: is tagged by udev as: Keyboard
[ 32.988] (II) event0 - Power Button: device is a keyboard
[ 32.989] (II) config/udev: Adding input device HDA NVidia HDMI/DP,pcm=9 (/dev/input/event10)
[ 32.989] (II) No input driver specified, ignoring this device.
[ 32.989] (II) This device may have been added with another device file.
[ 32.990] (II) config/udev: Adding input device HDA NVidia HDMI/DP,pcm=3 (/dev/input/event7)
[ 32.990] (II) No input driver specified, ignoring this device.
[ 32.990] (II) This device may have been added with another device file.
[ 32.991] (II) config/udev: Adding input device HDA NVidia HDMI/DP,pcm=7 (/dev/input/event8)
[ 32.991] (II) No input driver specified, ignoring this device.
[ 32.991] (II) This device may have been added with another device file.
[ 32.991] (II) config/udev: Adding input device HDA NVidia HDMI/DP,pcm=8 (/dev/input/event9)
[ 32.992] (II) No input driver specified, ignoring this device.
[ 32.992] (II) This device may have been added with another device file.
[ 32.992] (II) config/udev: Adding input device HDA Intel MID Front Mic (/dev/input/event11)
[ 32.992] (II) No input driver specified, ignoring this device.
[ 32.992] (II) This device may have been added with another device file.
[ 32.993] (II) config/udev: Adding input device HDA Intel MID Rear Mic (/dev/input/event12)
[ 32.993] (II) No input driver specified, ignoring this device.
[ 32.993] (II) This device may have been added with another device file.
[ 32.993] (II) config/udev: Adding input device HDA Intel MID Line (/dev/input/event13)
[ 32.993] (II) No input driver specified, ignoring this device.
[ 32.993] (II) This device may have been added with another device file.
[ 32.994] (II) config/udev: Adding input device HDA Intel MID Line Out Front (/dev/input/event14)
[ 32.994] (II) No input driver specified, ignoring this device.
[ 32.994] (II) This device may have been added with another device file.
[ 32.995] (II) config/udev: Adding input device HDA Intel MID Line Out Surround (/dev/input/event15)
[ 32.995] (II) No input driver specified, ignoring this device.
[ 32.995] (II) This device may have been added with another device file.
[ 32.995] (II) config/udev: Adding input device HDA Intel MID Line Out CLFE (/dev/input/event16)
[ 32.995] (II) No input driver specified, ignoring this device.
[ 32.995] (II) This device may have been added with another device file.
[ 32.996] (II) config/udev: Adding input device HDA Intel MID Line Out Side (/dev/input/event17)
[ 32.996] (II) No input driver specified, ignoring this device.
[ 32.996] (II) This device may have been added with another device file.
[ 32.997] (II) config/udev: Adding input device HDA Intel MID Front Headphone (/dev/input/event18)
[ 32.997] (II) No input driver specified, ignoring this device.
[ 32.997] (II) This device may have been added with another device file.
[ 32.998] (II) config/udev: Adding input device Logitech Gaming Mouse G600 (/dev/input/event3)
[ 32.998] (**) Logitech Gaming Mouse G600: Applying InputClass "evdev pointer catchall"
[ 32.998] (**) Logitech Gaming Mouse G600: Applying InputClass "libinput pointer catchall"
[ 32.998] (II) Using input driver 'libinput' for 'Logitech Gaming Mouse G600'
[ 33.056] (II) systemd-logind: got fd for /dev/input/event3 13:67 fd 33 paused 0
[ 33.056] (**) Logitech Gaming Mouse G600: always reports core events
[ 33.056] (**) Option "Device" "/dev/input/event3"
[ 33.056] (**) Option "_source" "server/udev"
[ 33.059] (II) event3 - Logitech Gaming Mouse G600: is tagged by udev as: Mouse
[ 33.059] (II) event3 - Logitech Gaming Mouse G600: device is a pointer
[ 33.060] (II) event3 - Logitech Gaming Mouse G600: device removed
[ 33.060] (**) Option "config_info" "udev:/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.0/0003:046D:C24A.0001/input/input3/event3"
[ 33.060] (II) XINPUT: Adding extended input device "Logitech Gaming Mouse G600" (type: MOUSE, id 8)
[ 33.060] (**) Option "AccelerationScheme" "none"
[ 33.060] (**) Logitech Gaming Mouse G600: (accel) selected scheme none/0
[ 33.060] (**) Logitech Gaming Mouse G600: (accel) acceleration factor: 2.000
[ 33.060] (**) Logitech Gaming Mouse G600: (accel) acceleration threshold: 4
[ 33.062] (II) event3 - Logitech Gaming Mouse G600: is tagged by udev as: Mouse
[ 33.062] (II) event3 - Logitech Gaming Mouse G600: device is a pointer
[ 33.063] (II) config/udev: Adding input device Logitech Gaming Mouse G600 (/dev/input/mouse0)
[ 33.063] (II) No input driver specified, ignoring this device.
[ 33.063] (II) This device may have been added with another device file.
[ 33.065] (II) config/udev: Adding input device Logitech Gaming Mouse G600 Keyboard (/dev/input/event4)
[ 33.065] (**) Logitech Gaming Mouse G600 Keyboard: Applying InputClass "evdev keyboard catchall"
[ 33.065] (**) Logitech Gaming Mouse G600 Keyboard: Applying InputClass "libinput keyboard catchall"
[ 33.065] (II) Using input driver 'libinput' for 'Logitech Gaming Mouse G600 Keyboard'
[ 33.066] (II) systemd-logind: got fd for /dev/input/event4 13:68 fd 34 paused 0
[ 33.067] (**) Logitech Gaming Mouse G600 Keyboard: always reports core events
[ 33.067] (**) Option "Device" "/dev/input/event4"
[ 33.067] (**) Option "_source" "server/udev"
[ 33.069] (II) event4 - Logitech Gaming Mouse G600 Keyboard: is tagged by udev as: Keyboard
[ 33.069] (II) event4 - Logitech Gaming Mouse G600 Keyboard: device is a keyboard
[ 33.069] (II) event4 - Logitech Gaming Mouse G600 Keyboard: device removed
[ 33.069] (**) Option "config_info" "udev:/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.2/2-1.2:1.1/0003:046D:C24A.0002/input/input4/event4"
[ 33.069] (II) XINPUT: Adding extended input device "Logitech Gaming Mouse G600 Keyboard" (type: KEYBOARD, id 9)
[ 33.071] (II) event4 - Logitech Gaming Mouse G600 Keyboard: is tagged by udev as: Keyboard
[ 33.071] (II) event4 - Logitech Gaming Mouse G600 Keyboard: device is a keyboard
[ 33.073] (II) config/udev: Adding input device Logitech Gaming Mouse G600 (/dev/input/event5)
[ 33.073] (II) No input driver specified, ignoring this device.
[ 33.073] (II) This device may have been added with another device file.
[ 33.074] (II) config/udev: Adding input device AT Translated Set 2 keyboard (/dev/input/event2)
[ 33.074] (**) AT Translated Set 2 keyboard: Applying InputClass "evdev keyboard catchall"
[ 33.074] (**) AT Translated Set 2 keyboard: Applying InputClass "libinput keyboard catchall"
[ 33.074] (II) Using input driver 'libinput' for 'AT Translated Set 2 keyboard'
[ 33.074] (II) systemd-logind: got fd for /dev/input/event2 13:66 fd 35 paused 0
[ 33.074] (**) AT Translated Set 2 keyboard: always reports core events
[ 33.074] (**) Option "Device" "/dev/input/event2"
[ 33.074] (**) Option "_source" "server/udev"
[ 33.075] (II) event2 - AT Translated Set 2 keyboard: is tagged by udev as: Keyboard
[ 33.075] (II) event2 - AT Translated Set 2 keyboard: device is a keyboard
[ 33.076] (II) event2 - AT Translated Set 2 keyboard: device removed
[ 33.076] (**) Option "config_info" "udev:/sys/devices/platform/i8042/serio0/input/input2/event2"
[ 33.076] (II) XINPUT: Adding extended input device "AT Translated Set 2 keyboard" (type: KEYBOARD, id 10)
[ 33.077] (II) event2 - AT Translated Set 2 keyboard: is tagged by udev as: Keyboard
[ 33.078] (II) event2 - AT Translated Set 2 keyboard: device is a keyboard
[ 33.079] (II) config/udev: Adding input device PC Speaker (/dev/input/event6)
[ 33.079] (II) No input driver specified, ignoring this device.
[ 33.079] (II) This device may have been added with another device file.
[ 33.814] (II) NVIDIA(GPU-0): Display (Samsung S23B550 (DFP-1)) does not support NVIDIA 3D
[ 33.814] (II) NVIDIA(GPU-0): Vision stereo.
[ 35.731] (II) NVIDIA(GPU-0): Display (Samsung S23B550 (DFP-1)) does not support NVIDIA 3D
[ 35.731] (II) NVIDIA(GPU-0): Vision stereo.
[ 41.601] (**) Option "fd" "29"
[ 41.601] (II) event1 - Power Button: device removed
[ 41.601] (**) Option "fd" "32"
[ 41.601] (II) event0 - Power Button: device removed
[ 41.602] (**) Option "fd" "33"
[ 41.602] (II) event3 - Logitech Gaming Mouse G600: device removed
[ 41.602] (**) Option "fd" "34"
[ 41.602] (II) event4 - Logitech Gaming Mouse G600 Keyboard: device removed
[ 41.603] (**) Option "fd" "35"
[ 41.603] (II) event2 - AT Translated Set 2 keyboard: device removed
[ 41.886] (II) systemd-logind: got pause for 13:64
[ 41.887] (II) systemd-logind: got pause for 13:67
[ 41.887] (II) systemd-logind: got pause for 13:66
[ 41.887] (II) systemd-logind: got pause for 13:65
[ 41.887] (II) systemd-logind: got pause for 13:68
[ 50.836] (II) UnloadModule: "libinput"
[ 50.836] (II) systemd-logind: releasing fd for 13:66
[ 50.853] (II) UnloadModule: "libinput"
[ 50.853] (II) systemd-logind: releasing fd for 13:68
[ 50.876] (II) UnloadModule: "libinput"
[ 50.876] (II) systemd-logind: releasing fd for 13:67
[ 50.912] (II) UnloadModule: "libinput"
[ 50.912] (II) systemd-logind: releasing fd for 13:64
[ 50.924] (II) UnloadModule: "libinput"
[ 50.924] (II) systemd-logind: releasing fd for 13:65
[ 50.959] (II) NVIDIA(GPU-0): Deleting GPU-0
[ 50.962] (II) Server terminated successfully (0). Closing log file.

Judging from the output I assume, that you are running gnome on xorg [1]?
Can you elaborate how you start your session and whether you have modified the configuration of gdm?

If you do run gnome on xorg you could try e.g. `QT_QPA_PLATFORM=xcb qjackctl`.
If you are running the default gnome session (which will be wayland), you probably need to either install xorg-xwayland or you start qjackctl as a native wayland application (i.e. `QT_QPA_PLATFORM=wayland qjackctl`).

Please let us know, what works for you.

[1] https://wiki.archlinux.org/index.php/GNOME#GNOME_Sessions

Hello.
I have xorg-wayland installed
pikaur -Qs xorg-xwayland
local/xorg-xwayland 21.1.0-1 (xorg)
run X clients under wayland

$ QT_QPA_PLATFORM=xcb qjackctl
Segmentation fault (core dumped)

$ QT_QPA_PLATFORM=wayland qjackctl
Failed to create wl_display (No such file or directory)
qt.qpa.plugin: Could not load the Qt platform plugin "wayland" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.

Aborted (core dumped)


cadence works (Also cadence with no env):
$ QT_QPA_PLATFORM=xcb cadence
Using Tray Engine 'Qt'
qt.qpa.xcb: QXcbConnection: XCB error: 5 (BadAtom), sequence: 456, resource id: 0, major code: 20 (GetProperty), minor code: 0

THIS CRASH:
$ QT_QPA_PLATFORM=wayland cadence
Using Tray Engine 'Qt'
Failed to create wl_display (No such file or directory)
qt.qpa.plugin: Could not load the Qt platform plugin "wayland" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: dxcb, xcb, eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, webgl.

Aborted (core dumped)

I did make qjackctl from source code (configure && make ) and it works:
luca@i5:~/tmp/qjackctl/qjackctl-0.9.2$ src/qjackctl
I copied the qjackctl in /usr/bin

Maybe some lib problems?

@acul71: It seems you are using an unsupported graphics driver [1].

Please try and raise your issues on the AUR or in a post on our forums. Unfortunately we can not provide support for this here.

[1] https://aur.archlinux.org/packages/nvidia-340xx/