使用用户模型在环回中获得401错误

I have list of more than 5k users in my another DB, and I want to migrate all the users in loopback DB, there are many duplicate users exists so that I am checking if user exists then I am updating a user otherwise I am creating new one. I have written a script for that. Its working fine but after updates first user, loopback starts throwing an error 401 Unauthorized if I execute GET user detail API. Even I have allowed Unauthenticated user to access update, create property with ACL, but its not working with this as well.I have list of more than 5k users in my another