*** WARNING *** The docker service has not been restarted. In the migration from docker<1.10.0 to docker>=1.10.0, the Docker image format has changed to be completely content-addressible. This results in several positive improvements to image operations (better caching during builds mainly). However, the migration operation may take several hours if you have a lot of large images on a Docker host. In order to ensure that you have minimum downtime, the docker service has not been restarted as it will trigger this migration. You may either restart this service at a time of your choosing or manually run the separate migration tool (which will not cause downtime for your Docker daemon). You can run the migration with this command, which will exit after the migration has been completed: $ %{_libexecdir}/docker-image-migrator/do-image-migration-v1to2.sh Because the migrator requires information about the storage driver used by Docker, the migration script will source %{_sysconfdir}/sysconfig/docker and use \$DOCKER_OPTS as arguments to the migrator. If this automated migration fails, it will be re-attempted with every known storage driver. In addition, the script accepts arguments which will simiarly be appended to the set of arguments (after \$DOCKER_OPTS) to the migrator. Restarting docker without running this separate migration tool, WILL CAUSE DOWNTIME, BECAUSE DOCKER WILL RUN THE MIGRATION ON FIRST START AND YOU WILL BE UNABLE TO START ANY CONTAINERS OR USE ANY DOCKER COMMANDS (EVEN CONTAINERS WITH RESTART POLICIES ACTIVE):