Breaking changes (Engine)
Breaking changes and incompatibilities
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.
Engine 1.12
Docker clients <= 1.9.2 used an invalid Host header when making request to the daemon. Docker 1.12 is built using golang 1.6 which is now checking the validity of the Host header and as such clients <= 1.9.2 can’t talk anymore to the daemon. An environment variable was ad