Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 11910 (unattended-upgr)...が発生する

VagrantでUbuntu20を動かしていて、apt upgrade時、以下のエラーが発生した。

Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 11910 (unattended-upgr)...

どうやら自動アップデートが裏でうごいていたっぽい。

$ ps aux | grep upgrade
root         755  0.0  0.2 108104 20700 ?        Ssl  May08   0:00 /usr/bin/python3 /usr/share/unattended-upgrades/unattended-upgrade-shutdown --wait-for-signal
root       12332 13.6  1.9 316808 156352 ?       Rl   07:58   0:05 /usr/bin/python3 /usr/bin/unattended-upgrade
root       23469 15.0  1.2 316808 99780 ?        S    07:58   0:00 /usr/bin/python3 /usr/bin/unattended-upgrade
root       23705  0.0  0.6 316808 56220 ?        S    07:58   0:00 /usr/bin/python3 /usr/bin/unattended-upgrade
vagrant    23734  0.0  0.0   8160   724 pts/0    R+   07:58   0:00 grep --color=auto upgrade

自動アップデートを切りたい場合は以下を0にしてあげましょう。

$  cat /etc/apt/apt.conf.d/20auto-upgrades
APT::Periodic::Update-Package-Lists "1";
APT::Periodic::Unattended-Upgrade "1";