Docker error: client and server don't have same version

It looks like you need to upgrade the VM after installing boot2docker:

if you are upgrading from boot2docker 0.12 or later, you can update your existing virtual machine (after upgrading using the installer) using boot2docker stop && boot2docker download && boot2docker up - and you will not lose your existing data.

(https://github.com/boot2docker/osx-installer/releases/tag/v1.1.0)

This can happen if you have updated Docker, but the service has not been restarted. You will then try to connect to the Docker daemon with the updated client, while the daemon (that was already running before the update) is still running the older version.

To fix this, restart the service:

sysV init:

service docker restart

systemd:

systemctl daemon-reload

systemctl restart docker

In case you use docker-machine to manage a local VirtualBox-based machines the solution is as simple as for boot2docker:

docker-machine upgrade MACHINE_NAME

It asks docker-machine to download the latest boot2docker.iso and place it as a new root filesystem in the upgraded VM.

By the way, the VirtualBox-backed docker machine has its root filesystem readonly. That mean it's not possible for any manual update survive the machine reboot. That was a surprise for me.