By backing up and restoring a user pool, the sensitive credentials (TOTP, passwords) of any users are stripped away. To authenticate them with our app, in practical terms, they need to set a password again.

Problem is that I don't know how to achieve this technically. When I attempt to log in to a user who has been migrated/restored, the client recieves a DTO:

{
"ChallengeName": "PASSWORD_VERIFIER",
  "ChallengeParameters": {
    "SALT": "",
    "SECRET_BLOCK": ""
    "SRP_B": "",
    "USERNAME": "",
    "USER_ID_FOR_SRP": ""
  }
}

I understand that the Client needs to fulfill this challenge, but I have been unable to find any documentation or guides online on how to correctly respond.

Please help me out?