On January 15, 2016, the Docker devs announced the release of the first RC (Release Candidate) build for Docker 1.10, informing users about some important tips on updating engines and migrating images to new IDs, as the new version of the Docker Engine will store filesystem data and images in containers a bit differently.
How differently might you ask? Well, Docker 1.10 will provide a more secure foundation for writing layers and images, a migration step will be available when upgrading old images, there will be a new distribution manifest, along with pull functionality, as well as a migration tool for minimizing the migration time.