Despite having performed the solution suggested in the line below, the autostart of my LXCs does not work under Debian Buster when the machine is rebooted.
Without reboot of the machine it works but if I reboot the machine systemctl does not work anymore. I am required to start the LXCs with a lxc-start and then if I do a systemctl stop / start lxc it works.
After reboot systemctl start lxc not work
systemctl start lxc
lxc-ls -f
NAME STATE AUTOSTART GROUPS IPV4 IPV6 UNPRIVILEGED
cn1 STOPPED 1 - - - false
cn2 STOPPED 1 - - - false
cn3 STOPPED 1 - - - false
cn4 STOPPED 1 - - - false
cn5 STOPPED 1 - - - false
but if I do a manual lxc-start of my containers then a systemdctl stop / start lxc it works