"Page forbidden" specific case
As an administrator you can suppress rights from a user acount and apply changes by clicking "OK". The backend then displays a "forbidden page" message.
This messages occurs when ALL the rights associated to the administrator's group have been suppressed BUT the user's profile still exists.
Let's take an example.
This user has rights on both the Customer group and the Sigfox_France domain :
From the workspace administrator's side the Sigfox_France domain rights do not appear.
The administrator suppresses all user's rights on his group :
The user then has the following rights :
And when the administrator applies changes the backend displays :
This message is displayed because the backend is trying to display the user's information page but the administrator has no rights on the Sigfox_France group.