You can prevent the creation of new user sessions while keeping the already started user sessions untouched. This is especially useful if you plan to shutdown your server in the near future and if you do not want to close the sessions of already connected users abruptly.

Preventing the creation of new user sessions is done by setting the global setting User sessions & security: Allow new user sessions to false. If this setting false the Application Server will prevent new sessions from being created, except if the user who wants to create the session has the system permission Create user session when server is closed (13). Currently active sessions will not be affected.