Provider docker not found - Vagrant

Question

Whenever I run vagrant up --provider=docker, I get this error message.

The provider 'docker' could not be found, but was requested to
back the machine 'default'.

But, when i run Docker himself, without vagrant everything works fine.

I'm on Linux Mint Rebecca. All is updated.

Vagrantfile

# -*- mode: ruby -*-
# vi: set ft=ruby :

# Vagrantfile API/syntax version. Don't touch unless you know what you're doing!
VAGRANTFILE_API_VERSION = "2"

Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
  config.vm.network :private_network, ip: "192.168.33.10"
  config.vm.synced_folder "./", "/vagrant_data"
  config.vm.provider "docker" do |d|
    d.image = "ubuntu"
  end
end

Answer 1

After a completely reinstall (vagrant and docker), it works. :)