LXC containers are not working on 18:04

I recently upgraded from Ubuntu 16:04 to 18:04 on Linode using a do-release-upgrade.
I had few containers working which have stopped.
lxc --version is 3.0.4 on machine name delta-clone
Well tried to move the containers to Ubuntu 20 machine and used lxc import the *.tar under folder container but that did not help. lxc version is 4.0 on machine name jira
Had anew Linode with Ubuntu16.04 and 2.0.16 but does not work machine name topaz jira
Can any one help please?