Welcome to Docker ;) In Dockerland, all container image repositories (i.e. "folders") must be in a namespace. library is a reserved namespace, and it's synonymous with with _ and (empty). This means, when you do something like ,docker pull ubuntu, the client will translate that to library/ubuntu , then request it from the registry. Same thing with push. You should avoid using library (or (empty) namespaces) for your own container images. Just put your own company name in. FYI, we have some big plans with making this a lot easier to work with in the future, stay tuned!