Hi @Gunjan.Parmar ,
Thank you for posting this topic on the Auth0 Community!
The email and phone_number are associated with Email and SMS connections respectively. They are the two types of connections for the Passwordless Authentication.
A user can have either the SMS connection type, for which we can only update the phone number, or the Email connection type, for which we can only update the email. Therefore we can not update both fields simultaneously.
Hope this helps!