Original forum post: https://musescore.org/en/node/309365

Official MuseScore AppImage always throws segmentation fault when trying to enabling MIDI input. Due to this issue, I cannot use MIDI input at all currently.
Environment:

MuseScore 3.5.0 stable, official AppImage build.
Manjaro Linux

Reproduce Steps

Method 1

1. Default setting is Pulse Audio, no MIDI input support
2. Preference -> I/O -> choose Port Audio (API=ALSA, Device=default) -> Apply
3. Restart application
4. Create new file or open existing file
5. Click Toggle "MIDI Input" -> 100% crash immediately (segmentation fault)

~/Applications/MuseScore-3.5.0-x86_64_e65918732aaa7fb723a07f738e11134b.AppImage --debug                                                                                                                                                                                                                         (08-20 17:12)
/usr/lib/libjack.so.0
/usr/lib/libnss3.so
ALSA lib pcm_dsnoop.c:642:(snd_pcm_dsnoop_open) unable to open slave
ALSA lib pcm_dmix.c:1090:(snd_pcm_dmix_open) unable to open slave
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
connect(2) call to /dev/shm/jack-1000/default/jack_0 failed (err=No such file or directory)
attempt to connect to server failed
connect(2) call to /dev/shm/jack-1000/default/jack_0 failed (err=No such file or directory)
attempt to connect to server failed
ALSA lib pcm_oss.c:377:(_snd_pcm_oss_open) Unknown field port
ALSA lib pcm_oss.c:377:(_snd_pcm_oss_open) Unknown field port
ALSA lib pcm_usb_stream.c:486:(_snd_pcm_usb_stream_open) Invalid type for card
ALSA lib pcm_usb_stream.c:486:(_snd_pcm_usb_stream_open) Invalid type for card
ALSA lib pcm_dmix.c:1090:(snd_pcm_dmix_open) unable to open slave
connect(2) call to /dev/shm/jack-1000/default/jack_0 failed (err=No such file or directory)
attempt to connect to server failed
/tmp/.mount_MuseSc2NWnUc/AppRun: line 26:  3989 Segmentation fault      (core dumped) "${APPDIR}/bin/mscore-portable" "$@"

Method 2

1. Default setting is Pulse Audio, no MIDI input support
2. Preference -> I/O -> choose Port Audio (API=ALSA, Device=default) -> Apply -> Restart Audio and MIDI Devices -> 100% crash immediately (segmentation fault)

~/Applications/MuseScore-3.5.0-x86_64_e65918732aaa7fb723a07f738e11134b.AppImage --use-audio portaudio --debug                                                                                                                                                                                                   (08-20 17:40)
/usr/lib/libjack.so.0
/usr/lib/libnss3.so
ALSA lib pcm_dsnoop.c:642:(snd_pcm_dsnoop_open) unable to open slave
ALSA lib pcm_dmix.c:1090:(snd_pcm_dmix_open) unable to open slave
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
connect(2) call to /dev/shm/jack-1000/default/jack_0 failed (err=No such file or directory)
attempt to connect to server failed
connect(2) call to /dev/shm/jack-1000/default/jack_0 failed (err=No such file or directory)
attempt to connect to server failed
ALSA lib pcm_oss.c:377:(_snd_pcm_oss_open) Unknown field port
ALSA lib pcm_oss.c:377:(_snd_pcm_oss_open) Unknown field port
ALSA lib pcm_usb_stream.c:486:(_snd_pcm_usb_stream_open) Invalid type for card
ALSA lib pcm_usb_stream.c:486:(_snd_pcm_usb_stream_open) Invalid type for card
ALSA lib pcm_dmix.c:1090:(snd_pcm_dmix_open) unable to open slave
connect(2) call to /dev/shm/jack-1000/default/jack_0 failed (err=No such file or directory)
attempt to connect to server failed
ALSA lib pcm.c:8545:(snd_pcm_recover) underrun occurred
/tmp/.mount_MuseScE8tyFs/AppRun: line 26:  6729 Segmentation fault      (core dumped) "${APPDIR}/bin/mscore-portable" "$@"