Cannot register custom host

Trying to get the new rancher beta agent on one of our bare metal hosts to test, however i cannot get it to register. Get this each time i try

time="2018-05-01T23:52:55Z" level=info msg="Error while getting agent config: invalid response 500: secrets \"c-cluster-mw9ss\" not found"
time="2018-05-01T23:53:00Z" level=info msg="Error while getting agent config: invalid response 500: secrets \"c-cluster-mw9ss\" not found"
evel=info msg="Error while getting agent config: invalid response 500: secrets \"c-cluster-mw9ss\" not found"

Running the supported version of docker on the host

root@phx2-1:~# docker --version
Docker version 17.03.2-ce, build f5ec1e2

Anybody seen this?