I was using the following instructions on 3.4.d :
Controlling who can create sites
By default any authenticated user can create sites in Share. The creator of the new site is given the Site Manager role and they control who has access to the site and in what role.
If an admin user wants to limit who can create sites, they can do this by managing node permissions in the normal way. All sites are created as nodes of type st:site under a fixed "site root object" - the "Sites" folder under "Company Home". An admin user can change the permissions on this "Sites" node in order to restrict who has the ability to create children and hence create new sites.
In Alfresco 3.3 and earlier, the admin user must login to the Alfresco Explorer client in order to manage the permissions of the Sites root object. Starting with Alfresco 3.4, they can access the repository nodes and manage their permissions without leaving Share.
By default, the "everyone" authority has a Contributor role on the Sites node. You can remove "everyone" from this node's permissions and replace it with different users or groups of your choosing.
For example, you could create a new group called SITE_CREATORS and give that group the Contributor role on the "Sites" node. In that way, only users who are members of the SITE_CREATORS groups will be able to create sites.
Of course, admin will always be able to create sites.
But I've upgrade to 4.0.a and now the default authority is Consumer instead of Contributor and Consumer and Consumers apparently are allowed to create sites. I need help. If I remove the Everyone = Consumer then i get "Internal Error".