vRanger cannot add host credentials to a host, which was recently upgraded to ESX 4.x/5.x from ESX 3.5. If the user isn't "root", vRanger throws the following error: "-1 - User <username*> could not be authenticated". If the user is "root", then vRanger throws the following error: "Authentication token manipulation error".
1. If the user to credential host isn't "root", then open vSphere Client and connect directly to the host (not the Virtual Center), then go to "Local Users & Groups" tab > right-click on that specific user and select "Edit". Under "Group membership" you should see 2 groups: "users" and "root". If one of them is missing, please select the missing group from "Select Group" drop-down list and then click on "Add" button. After that is done, click OK and try to add host credentials again.
2. If the user to credential host is "root", please follow up this KB (ESX and ESXi 4.x and 5.x password requirements and restrictions):
