When installing docker-ce on fedora 31 it does not work out of the box as Fedora 31 uses cgroups v2 by default and docker doesn’t yet support cgroupsv2.
To solve this, edit grub config:
sudo gedit /etc/default/grub
Add the parameter systemd.unified_cgroup_hierarchy=0 to the line starting by GRUB_CMDLINE_LINUX
Now update grub by running:
grub2-mkconfig
And reboot the system.