Unable to use Password Realm Grant Type despite having Essentials Plan with Home Realm Discovery

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1

Hello,

I’m trying to implement the Resource Owner Password Flow with realm support for my application, but I’m encountering issues with the password-realm grant type.

My setup:

  • Plan: B2B Essentials (includes Home Realm Discovery feature)
  • Application: Tests Eric (Client ID: 1234)
  • Multiple database connections per application (tests-eric, client1, client2, etc.)

The problem: I need to use different database connections for different applications without setting a global Default Directory at the tenant level. According to your documentation, I should be able to use:

grant_type=http://auth0.com/oauth/grant-type/password-realm
realm=tests-eric

However, when I attempt this request, I get:

{"error":"unauthorized_client","error_description":"Grant type 'http://auth0.com/oauth/grant-type/password-realm' not allowed for the client."}

Questions:

  1. How do I enable the password-realm grant type for my application?
  2. I don’t see this option in Applications → Advanced Settings → Grant Types
  3. Is there additional configuration needed to activate Home Realm Discovery?

What works:

  • Regular Password Grant works when I set a Default Directory globally
  • But I cannot use a global Default Directory due to multiple isolated applications

Could you please help me configure the Password Realm grant type for my application?

Thank you for your assistance.

Best regards, Eric

3

Hi @EBA,

Welcome to the Auth0 Community and thank you for your post!

The reason for this error should be enabling the password grant directly via the Management API, which will not enable the https://auth0.com/oauth/grant-type/password-realm as well. This Knowledge article - Error “Grant type ‘https://auth0.com/oauth/grant-type/password-realm’ not allowed for the client” specifies 2 possible solutions for this error:

  • Turn the ‘Password’ grant type off > Save > and then on again > Save in the dashboard.

  • update the client via the Management API using a command such as this:

curl -L -X PATCH 'https://YOUR-DOMAIN.auth0.com/api/v2/clients/YOUR-CLIENT-ID' \

-H 'Content-Type: application/json' \

-H 'Accept: application/json' \

-H 'Authorization: Bearer 🔒' \

-d '{"grant_types":["password","http://auth0.com/oauth/grant-type/password-realm"]}'

I hope this helps!
Thanks,
Remus