The Security layer is not set to RDP on the target server.
To resolve this issue, perform the following procedure on the target server:
• Open the Local Group Policy Editor by typing "gpedit.msc" into either a Run prompt or the Start menu
• In the Local Group Policy Editor, select Local Computer Policy > Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktop Session Host > Security
• Enable "Require use of specific security layer for remote (RDP) connections" and set the security layer to RDP
Note: Alternatively, open HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlTerminal ServerWinStationsRDP-Tcp in the Registry Editor, and set the Value data for SecurityLayer to 1.