Changing IMM UserID and PW on IBM Server Failed

I have an IBM 3650 M2 where I am unable to change the IMM's username and password. If I try to create another supervisor account so I can delete the original I get the message:

error communication to server: CreateAccount Failed in the backend

I have not found much in the way of online resources that gives a clear picture why is this is happened, and how to resolve it.