I too encountered this same problem today, after a package upgrade from 5:20.10.5~3-0~ubuntu-bionic to 5:20.10.6~3-0~ubuntu-bionic. I too have ipv6 disabled in the kernel:
$ cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-4.15.0-112-generic root=/dev/mapper/main-root ro ipv6.disable=1 nomdmonddf nomdmonisw cgroup_enable=memory swapaccount=1
And downgrading docker-ce and docker-ce-cli got rid of the problem for the moment.