Error: "No synced folder implementation is available for your synced folders!"

[cgoldammer]

The full output is

No synced folder implementation is available for your synced folders!
Please consult the documentation to learn why this may be the case.
You may force a synced folder implementation by specifying a "type:"
option for the synced folders. Available synced folder implementations
are listed below.

docker, nfs, rsync, smb, virtualbox

I obtain this error when running vagrant up --provider=rackspace on Windows 7.

My Vagrantfile looks as follows:

Vagrant.configure("2") do |config|
  config.vm.box = "hashicorp/precise32"
  config.vm.synced_folder "synced", "/var/www/synced"
  config.vm.provider :rackspace do |rs|
    rs.username = "..."
    rs.api_key = "..."
    rs.flavor = /512 MB Standard Instance/ 
    rs.image = /Ubuntu/
    rs.rackspace_region = :dfw
  end
end

If this is due to me mis-reading the documentation or added documentation can be helpful, I'd be happy to add that documentation.

[cgoldammer]

A quick update: Under Ubuntu, this did work. Thus, likely related to Windows.

[swarupdonepudi]

If this is a windows related issue, is there a possible fix that you can suggest?