This error must be caused by the version check becaus after adding ​​--storage-opt overlay2.override_kernel_check=1​​In ​​/etc/systemd/system/multi-user.target.wants/docker.service​​ I've got ´ExecStart=/usr/bin/dockerd --storage-driver=overlay2 --storage-opt overlay2.override_kernel_check=1` now.

I'll close this once I'm running the first images succesfully.