["The Client ID, Client Secret, and/or 3rd Party Application are incorrect" on token call]

I am getting the following error after auth while attempting to retrieve the token from POST https://api.intacct.com/ia/api/v1-beta2/oauth2/token.

{
  "code": "invalidRequest",
  "message": "The Client ID, Client Secret, and/or 3rd Party Application are incorrect",
  "errorId": "REST-1216",
  "additionalInfo": {
    "messageId": "IA.THE_CLIENT_ID_CLIENT_SECRET_AND_OR_3RD_PARTY_APPLICATION_ARE_INCORRECT",
    "placeholders": {},
    "propertySet": {}
  },
  "supportId": "L5sQ7EB069%7EZfnxgP0d2_--9iMWOkbWGgAAAAI"
}

 

 

Request Body (redact [...])

1. grant_type: "authorization_code"
2.  code: "eyJhbGciOiJ[...]"
3.  redirect_uri: "https://www.getpostman.com/oauth2/callback"
4.  client_id: "8b[...].app.sage.com"
5.  client_secret: "bd[...]"