Sometimes things break. You can find the most recent errors using a combination of journalctl, along with the classic tools sort and uniq.

journalctl --no-pager --since today --grep 'fail|error|fatal' --output json | jq '._EXE' | sort | uniq -c | sort --numeric --reverse --key 1

Sample Output
898172 "/usr/bin/dockerd"
752 "/usr/local/sbin/node_exporter"
30 "/usr/bin/gnome-shell"
26 "/usr/bin/cat"
22 "/usr/libexec/gsd-media-keys"
[...]