OAUTH Confidential Client stuck in "Client not enabled" state

UK Developers
1

I am building a personal Python-based bot to monitor my own account balance. I am trying to implement the OAuth 2.0 flow using a Confidential Client to handle token refreshing automatically.

I am hitting a blocker where I cannot exchange my authorisation code for an access token.

I am successfully obtaining an authorization code. However, when my application sends the POST request to exchange this code for a token, it fails immediately.

  • Endpoint: https://api.monzo.com/oauth2/token

  • Request Type: POST

  • Parameters: grant_type=authorization_code, client_id=..., code=...

The Response:

JSON

{
  "code": "bad_request.client_not_enabled",
  "error": "invalid_request",
  "error_description": "Client not enabled",
  "message": "Client not enabled"
}

Steps Tried:

  1. Created a new Confidential Client in the Developer Portal.

  2. I successfully receive the “Login/Approval Request” notification for the OAUTH app in my Monzo mobile app and approve it.

  3. I have tried deleting and recreating the client multiple times (clearing cookies/sessions in between).

Anything else I can do?