Following the migration to FreeRDP 2.0.0 via
GUACAMOLE-249, receipt of the Play Sound PDU causes the RDP connection to abort with an error:
guacd: DEBUG: DATA_PDU_TYPE_PLAY_SOUND - update_recv_play_sound() failed
guacd: DEBUG: rdp_recv_data_pdu() failed
guacd: DEBUG: transport_check_fds: transport->ReceiveCallback() - -1
guacd: DEBUG: freerdp_check_fds() failed - 0
guacd: ERROR: Connection closed.
This is because the newer version of FreeRDP requires a handler to be provided for the Play Sound PDU and will immediately close the connection if it receives this PDU without such a handler being assigned. Older versions of Windows, such as Windows Server 2003, will tend to send this PDU when audio is enabled, possibly causing the connection to close whenever an alert occurs.