Template: docker.io/restart Type: boolean Default: false Description: Automatically restart Docker daemon? If Docker is upgraded without restarting the Docker daemon, Docker will often have trouble starting new containers, and in some cases even maintaining the containers it is currently running. See https://launchpad.net/bugs/1658691 for an example of this breakage. . Normally, upgrading the package would simply restart the associated daemon(s). In the case of the Docker daemon, that would also imply stopping all running containers (which will only be restarted if they're part of a "service", have an appropriate restart policy configured, or have some other means of being restarted such as an external systemd unit).