Could not get lock

Another process holds the lock

ps aux | grep -E 'apt|dpkg' | grep -v grep
fuser -v /var/lib/dpkg/lock-frontend

Removing lock files while a transaction is in progress corrupts the package database. Wait for the process, or reboot if it is not running.

systemctl status unattended-upgrades --no-pager
grep -R delay /etc/apt/apt.conf.d/

dpkg --configure -a
apt-get -f install

Scope: failure mode: Package manager contention on a shared host.

CliHelper documents failure modes of third-party command line tools. No software is stored or distributed here.