Error "error: dpkg frontend is locked by another process"

sudo rm /var/lib//dpkg/lock
sudo dpkg --configure -a

ref:
https://www.ostechnix.com/how-to-fix-e-could-not-get-lock-var-lib-dpkg-lock-error-on-ubuntu/
https://www.youtube.com/watch?v=7GQIY37vPQ4