Disabling login to local admins does not prevent external sharing or even the creation of new users for external sharing. If login is disabled a new external user will be able to go through the complete creation workflow but the final login that enables the account will be denied. The error message does not specify why but only states "error - try again".
For this reason it is suggested to add a text or popup to the "Disable login to local accounts" screen to remind administrator to disable all external sharing when disabling login.
Also it would be nice if the login error message was changed to specify "local login disabled"

by: Kaare M. | over a year ago | Administration