I was on 1.10.3 and I had the remote api enabled by changing the $DOCKER_OPS from /etc/init/docker.conf to '-H tcp://0.0.0.0:4243 -H unix:///var/run/docker.sock', but now that doesn't work anymore!

I upgraded to Ubuntu Xenial (from Trusty) and docker engine from 1.10.3 to 1.12.1...

Any help is greatly appreciated!

EDIT: I reverted back to Upstart on this Ubuntu... still same issue.