Every Engine release strives to be backward compatible with its predecessors. In all cases, the policy is that feature removal is communicated two releases in advance and documented as part of the deprecated features page.
Unfortunately, Docker is a fast moving project, and newly introduced features may sometime introduce breaking changes and/or incompatibilities. This page documents these by Engine version.
There were two breaking changes in the 1.10 release.
Registry 2.3 includes improvements to the image manifest that have caused a
breaking change. Images pushed by Engine 1.10.0 to a Registry 2.3 cannot be
pulled by older Engine versions. A docker pull that encounters this situation
returns the following error:
Error response from daemon: unsupported schema version 2 for tag TAGNAME
Docker Content Trust heavily relies on image manifest formats. As a result, images pushed from the Engine 1.10 CLI to a 2.3 Registry have a manifest format which cannot be pulled by older Engine CLIs (< 1.10) with Docker Content Trust enabled.
If you are using an older Registry version (< 2.3), this problem does not occur with any version of the Engine CLI; push, pull, with and without content trust work as you would expect.
Engine older than the current 1.10.0 cannot pull images from repositories that have enabled key delegation. Key delegation is an experimental feature which requires a manual action to enable.