During deployments in an operations (Production/Live) environments, Microsoft Dynamics AX gives a very nice function to reject new users to log into the system, except the administrator who is online on the system right now.
From system administration, common forms, online users, server instance tab.
Click Reject new clients, a popup form will open as shown below.
The status will be changed from Alive, into Dragging.
In case of the administrator close the client by mistake he/she could not log into the client again, in that case you have to restart Microsoft Dynamics AX Service.
User group: DynamicsArabia