Error when using KeycloakAdmin assign_client_role

[Lucas08Ben]

I'm using that way:

keycloak_admin.assign_client_role(client_id=client_id,
                                      user_id=user_id,
                                      roles="role_name")

but it returns a type of error that I don't know how fix:

File ".venv/lib/python3.12/site-packages/keycloak/keycloak_admin.py", line 2723, in assign_client_role
    return raise_error_from_response("
File ".../.venv/lib/python3.12/site-packages/keycloak/exceptions.py", line 195, in raise_error_from_response
    raise error("
keycloak.exceptions.KeycloakPostError: 400: b'{"error":"unknown_error","error_description":"Cannot parse the JSON"}'

I'm using python-keycloak==5.3.1 and python==3.12
And the instance of keycloak is running the version 26.1.2