Please help !
duy tan, could you please share your code snippet creating user? Have you tried using postman to verify if the REST call is made correctly? BTW, how are you executing the script? Is it from outside of the ThingWorx Composer?
You can try testing the service CreateUser in Composer, catch the REST call with Developer Tools of Google Chrome (tab Network), then copy the call with Copy / Copy as cURL (bash)
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