Failure in migration to docker engine 1.10

Hi,

I have a VM that runs Ubuntu 14.04, with lxc-docker-1.9.1 installed on it.
When I upgrade my VM to a newer image that runs Ubuntu 18.04 and has docker .io on it, I expect that the docker graph will be migrated to engine 1.10, as described in https://docs.docker.com/engine/migration/.

I see 3 different behaviors, dependent on the docker .io version installed on the image:

  1. When I upgrade to an image with docker.io:18.09.5-0ubuntu1~18.04.2, everything works as expected.

  2. When I upgrade to an image with docker.io:18.09.7-0ubuntu1~18.04.4, the migration fails; I see in docker logs:

msg="Graph migration failed: \"migration is not supported\". Your old graph data was found to be too inconsistent for upgrading to content-addressable storage. Some of the old data was probably not upgraded. We recommend starting over with a clean storage directory if possible."
What does that error mean?

  1. When I upgrade to an image with docker.io:19.03.6-0ubuntu1~18.04.1, there is no migration at all; I saw in https://github.com/moby/moby/pull/38265 that the 1.10 migrator code was removed from 1.10 code ~2 years ago. Given that, is there anything I can do in order to migrate a graph from lxc-docker-1.9.1 to docker.io:19.03.6-0ubuntu1~18.04.1?

Thanks in advance,
Eitan