Rancher 503 Service Unavaiable

I am trying to set up a new cluster on an ESXi host and have come across an error I’ve not seen before, this happens after the creation of the cluster, I can see the VM created (powered off):

Error creating machine: Error in driver during machine creation: 503 Service Unavailable

ESXi Version: VMware ESXi, 6.7.0, 17700523
Rancher: 2.5.7


In my case this was due to a bad vmware template which wouldn’t start properly.