This article explains why the following error occurs when the 'password' grant type is enabled in the application, but the 'password-realm' grant type is not:

Grant type 'https://auth0.com/oauth/grant-type/password-realm' not allowed for the client

• Grant type

This error occurs when the 'password' grant is enabled in the client application, but 'https://auth0.com/oauth/grant-type/password-realm' is not. While enabling the Password grant type via the dashboard (under the application’s Advanced Settings) should enable both, it is possible to enable only one via the Management Application Programming Interface (API), which is the cause of this issue.

To resolve this issue, complete the following steps:

1. Navigate to the application's Advanced Settings in the dashboard.
2. Turn the Password grant type off and select the Save button.
3. Turn the Password grant type on and select the Save button.

If the issue persists, update the client via the Management API to ensure the “grant_types” array has both of the following grant types:

{ "grant_types": [ "password", "https://auth0.com/oauth/grant-type/password-realm", // any other additional grant types ] }