two issues with the same symptoms: 1/ after a reboot yesterday the statusbar shows the error in subject.
when I launch by hand sxmo_statusbar.sh I get an error: amixer: Unable to find simple control 'Master',0
the issue is in /usr/bin/sxmo_audiocurrentdevice.sh , amixer sget "Master" | grep -qE '[on]' && echo "Master" && return there's no master, so commenting that status bar works perfectly fine.
2/ probably due to modem status, sometimes after a reboot the same error appears and disappear if i wait a bit and reboot when the modem is online.
https://lists.sr.ht/~mil/sxmo-devel/patches/26847
This should fix the first issue.