On VyOS 1.3, when you try creating a new user, it works but it gives errors:
Version: VyOS 1.3-rolling-202007011734
set system login user test authentication plaintext-password "This.was.a.test"
Result:
adminuser@vyos# commit [ system login ] Configuration path: [system login user adminuser authentication plaintext-password ] is not valid Set failed Configuration path: [system login user adminuser authentication encrypted-password $6$grNMRfSrZYFvK.5O$85wk6DukaKwh4EKh6QbAnSJJMWvVOj5PLo5d9/JWbpMVrKWloADJYqhwIQoJwcrLiefDOJmtIsdD/Vmw9HdZe/] is not valid Set failed Configuration path: [system login user test authentication plaintext-password ] is not valid Set failed Configuration path: [system login user test authentication encrypted-password $6$1LSmLtVQQnkav4bl$ssyi1uTOChiMXaOdQ3FcpsCCLqXqdM6CTfLLpfv2FPrue9mGoFGp0n0BOnKi1PAtt9qaTdRLgUxiC7K/i5CGD.] is not valid Set failed
However, everything actually worked, it just gave these error messages.