"Could not get lock /var/lib/dpkg/lock-frontend" when installing apt packages

[janoskut]

Sometimes when running the firstboot scripts and installing apt packages, I'm getting this error:

E: Could not get lock /var/lib/dpkg/lock-frontend - open (11: Resource temporarily unavailable)
E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), is another process using it?

This is possibly because of apt-daily.service and apt-daily-upgrade.service also running on system start, as pointed out in this answer.

I think it would be a good idea to add apt-daily.service apt-daily-upgrade.service to After= in the service unit.

[nmcclain]

Added to main. THANK YOU!!